A Bazi chart records the innate energy state at the moment of a person's birth—the "genes" of destiny. However, a person's life spans decades. How does destiny unfold over this long period? This requires introducing the concepts of "Major Luck" (Da Yun) and "Annual Luck" (Liu Nian). Major Luck and Annual Luck are the core tools in Bazi destiny analysis for describing the temporal dimension of destiny; they transform the static chart into a dynamic life trajectory.

Major Luck refers to ten-year phases of life fortune. The arrangement of Major Luck uses the Months Pillar as the benchmark, with the direction (forward or reverse) determined by the gender of the person and the Yin-Yang nature of the Year Pillar. For Yang-year males and Yin-year females, it is arranged in forward order according to the Sexagenary Cycle; for Yin-year males and Yang-year females, it is arranged in reverse order. Each step of Major Luck governs ten years, proceeding through several steps to cover the entire life.

For example, a male born in a Yang year (Jia-Zi) with a Month Pillar of Bing-Yin would have his Major Luck arranged in forward order: the first step is Ding-Mao (ages 1–10), the second is Wu-Chen (ages 11–20), the third is Ji-Si (ages 21–30), and so on. The Heavenly Stem and Earthly Branch of each Major Luck step will interact with the Four Pillars of the chart through generation, restriction, clash, combination, punishment, and harm, thereby bringing changes in fortune during that phase.

The influence of Major Luck on the chart is slow and profound. Because each step governs ten years, it is like the "background" of life, determining the overall trend of that decade. If the Major Luck Stem and Branch are the Favorable Gods of the chart, then even if individual years within that decade are unfavorable, the overall period will still be relatively smooth. If the Major Luck Stem and Branch are the Unfavorable Gods, then even if there are a few good years within that decade, the overall period will still be relatively difficult.

Annual Luck refers to the Stem and Branch fortune of each specific year. The Annual Luck Stem and Branch directly interact with the chart and the Major Luck, bringing specific auspiciousness or misfortune for that particular year. For example, if a person encounters an Annual Luck year that clashes with the chart (Tian Ke Di Chong) during a certain Major Luck step, that year will likely bring significant changes or calamities. If the Annual Luck year forms a Three Combination or Six Combination with the chart, that year will likely bring happy events or benefactor assistance.

The relationship among Major Luck, Annual Luck, and the chart can be summarized as: "The chart is the body, Major Luck is the form, and Annual Luck is the function." The chart is the innate foundation, determining a person's basic structure and potential. Major Luck is the acquired fortune, determining the timing and phases of potential development. Annual Luck is the point of manifestation, determining the specific year in which events occur. Only by combining these three can one make a complete and accurate description of destiny.

When analyzing Major Luck and Annual Luck, destiny analysts typically focus on several aspects: first, whether the Major Luck and Annual Luck activate the "medicine" (Useful God) or the "disease" (Unfavorable God) in the chart; second, whether the Major Luck and Annual Luck form special combinations with the chart, such as Three Combination formations or Clash formations; third, whether the Major Luck and Annual Luck clash with or combine into the spouse palace, children palace, or parents palace in the chart.

For example, for a male chart where Direct Wealth represents the wife star, if an Annual Luck during a certain Major Luck step reveals Direct Wealth in the Heavenly Stem and combines into the spouse palace in the Earthly Branch, that year is very likely to be a marriage year. Another example: if a chart uses the Resource star as the Useful God, and during a certain Major Luck step the Annual Luck and Major Luck together restrict the Resource star, that year requires attention to the mother's health or setbacks in one's own academic or career pursuits.

The analysis of Major Luck and Annual Luck gives Bazi destiny analysis the ability to predict specific time periods. It is not a simple pronouncement of fatalism but a profound grasp of temporal rhythms. Understanding Major Luck and Annual Luck is understanding how destiny unfolds in the long river of time, understanding how the peaks and valleys of life alternate. This temporal dimension analysis is one of the most captivating aspects of the Ziping Method.

八字命盘记录的是一个人出生时的先天能量状态，是命运的"基因"。然而，人一生要经历数十年的时间，在这漫长岁月中，命运如何展开？这就需要引入"大运"和"流年"的概念。大运与流年，是八字命理学中描述命运时间维度的核心工具，它们将静态的命盘转化为动态的人生轨迹。

大运，是指人生中每十年一个阶段的运势。大运的排法以月柱为基准，根据命主的性别和年柱的阴阳属性决定顺排或逆排。阳年男命和阴年女命顺排，即按照六十甲子的顺序向后排列；阴年男命和阳年女命逆排，即按照六十甲子的顺序向前排列。每一步大运管十年，依次经历若干步大运，覆盖整个人生。

例如，某男命出生于甲子年（阳年），月柱为丙寅，则其大运顺排：第一步大运为丁卯（1-10岁），第二步大运为戊辰（11-20岁），第三步大运为己巳（21-30岁），以此类推。每一步大运的天干和地支，都会与命局中的四柱发生生克制化、刑冲合害的关系，从而带来该阶段运势的吉凶变化。

大运对命局的影响是缓慢而深远的。因为一步大运管十年，它如同人生的"大背景"，决定了这十年间的总体趋势。如果大运干支是命局的喜用神，则这十年间即便遇到个别不顺的年份，总体上也较为顺利；如果大运干支是命局的忌神，则这十年间即便有个别好年份，总体上也较为坎坷。

流年，是指每一年的干支运势。流年的天干和地支直接与命局和大运发生作用，带来具体年份的吉凶祸福。例如，某人在某步大运中，流年遇到与命局天克地冲的年份，往往该年会有较大的变动或灾咎；流年遇到与命局三合、六合的年份，往往该年会有喜事或贵人相助。

大运与流年、命局之间的关系，可以用"命局为体，大运为相，流年为用"来概括。命局是先天之本，决定了一个人的基本格局和潜能；大运是后天之运，决定了潜能发挥的时机和阶段；流年是应期之点，决定了具体事件发生的年份。三者结合，才能对命运做出完整而准确的描述。

在分析大运和流年时，命理师通常会关注以下几个方面：一是大运、流年是否引动了命局中的"药"（用神）或"病"（忌神）；二是大运、流年是否与命局形成特殊的组合，如三合局、冲克局等；三是大运、流年是否冲动了命局中的配偶宫、子女宫、父母宫等关键位置。

例如，一个男命以正财为妻星，若在某步大运中，流年天干透出正财，且地支合入配偶宫，则该年很可能结婚。又如，一个八字中以印星为用神，若在某步大运中，流年与大运共同克制印星，则该年需要注意母亲健康或自身学业、事业上的挫折。

大运与流年的分析，使八字命理学具有了预测具体时间段的功能。它不是宿命论的简单宣判，而是对时间节律的深刻把握。理解大运与流年，就是理解命运如何在时间的长河中展开，理解人生的高潮与低谷如何交替出现。这种时间维度的解析，是子平术最具魅力的部分之一。