Abstract:The genus Acer L. contains 200 species and is distributed in Asia, Europe, N Africa and N America, especially the Yangtze River Valley probably is a distribution center. The systematic evolution, origin and spread of Acer are discussed. The following hypotheses are suggested.(1) The Aceraceae is closely related Sapindaceae. The Acer L. is advanced genus in Aceraceae. (2) Based upon the primitive and typical plants, some plants of the genus Acer were evolved in direction of reduction or even of entire degeneration of the elements of flower, some others were specialized by increasing of the ele-ments of flower. (3) The evolutionary relationship of the four subgenera and twenty three sections of Acer are discussed. A figure showing their evolutionary relationship is provided. (4) The plants of Acer were found in the Jurassic in E Sichuan, Hubei, Hunan and neighbourhood in China, then spread to W Asia, Europ, N Africa and N America.