Abstract: This is a taxonomic study on the deciduous oaks of China by means of cluster and karyotype analyses. 1. By the cluster analysis to 25 species of the deciduous in China, 4 new taxa which have recently been published are further tested and their specific place in all the deciduous oaks are defined, and the relationship is quantified among the 25 oaks which are divided into two groups including daimyo oak group and sawtooth oak group. 2. The chromosome karyotypes of 12 main species of the deciduous oaks in China and common oak introduced are studied. The chromosomes of all the species exammed are 2n=24,and consist of metacentric and submetacentric chromosomes. The chromosomes from 1.14μ to 3.46μ in length. The 13species can be divided into three types:daimyo oak-type,sawtooth oak-type and common oak-type.