最大简约法（英语：Maximum parsimony）是一种常使用于系统发生学计算的方式，可用来根据分子串行的变异程度，来分析生物之间的演化关系，进而建构出演化树。

「简约」一般有「经济的」或「俭省的」之义，但在生物学中，「简约法」是属于无母数统计的一种统计方法以估计亲缘关系。以最大简约法建构的亲缘关系树是以演化过程具有最少次变化为前提，表示现存数据在过去的演化过程应由最少次步骤所形成。这项概念由Walter M. Fitch在1971年所提出。.

虽然演化过程并非必定由最少次步骤所形成，但普遍上认为较简约的步骤比起较繁复的步骤在演化过程中更容易发生。因此，「简约」的概念仍是建构亲缘关系的重要标准。

In phylogenetics, maximum parsimony is an optimality criterion under which the phylogenetic tree that minimizes the total number of character-state changes is to be preferred. Under the maximum-parsimony criterion, the optimal tree will minimize the amount of homoplasy (i.e., convergent evolution, parallel evolution, and evolutionary reversals). In other words, under this criterion, the shortest possible tree that explains the data is considered best. The principle is akin to Occam's razor, which states that—all else being equal—the simplest hypothesis that explains the data should be selected. Some of the basic ideas behind maximum parsimony were presented by James S. Farris in 1970 and Walter M. Fitch in 1971.