“等积原理”也称“祖暅原理”,历来被认为是祖暅最早提出的。本文通过对刘徽为《九章算术》所作注文的分析,揭示出刘徽先于祖暅大约两个半世纪就已认识到了此原理的一般形式。由此为“等积原理”正名,还历史以本来面目。 The principle of “equal product”, also known as the “principle of ancestry,” has historically been considered by the ancestral priest. This article analyzes the annotated text of Liu Huiwei’s “The Nine Chapters of Arithmetic” and reveals that Liu Huixian and Yu Zuyi had already realized the general form of this principle in about two and a half centuries. As a result, the “Equal Product Principle” has been renamed, and history has taken its original shape.