Abstract: To understand the genetic diversity of Yak populations from Tibetan and the relationship among them, a total of 33 polymorphic primers were used in RAPD analysis in 11 populations including Baqing Yak , Leiwuqi Yak, Dingqing Yak, Sangri Yak, Gongbujiangda Yak, Jiangda Yak, Kangbu Yak, Sangsang Yak, Jiali Yak, Pali Yak, Sibu Yak， 8 of them were selected for RAPD analysis of DNA of 11 Yak populations. Genetic distance indexes among breeds and genetic similarity indexes within breeds were calculated by Nei and the phylogenetic tree was constructed by UPGMA cluster analysis. The result showed that genetic diversity index of Tibet yak breeds or groups varied between 0.185 7 and 0.405 3. Among them Pali Yak was 0.185 7, which indicated that Pali Yak was relatively pure, the group was neat. And Gongbujiangda Yak was 0.405 3, which displayed that group internal have more variations. In 11 breeds or groups, the genetic diversity index respectively were: Gongbujiangda Yak(0.405 3)＞Jiangda Yak (0.353 6) ＞Sibu Yak(0.344 8)＞Kangbu Yak(0.342 8)＞Jiali Yak(0.332 3)＞Sangri Yak(0.282 3)＞Baqing Yak(0.279 3)＞Sangsang(0.269 8)＞Dingqing Yak(0.259 7)＞Leiwuqi Yak(0.224 1)＞Pali Yak(0.185 7). The eastern Tibet yak breeds or groups had higher genetic diversity, and the western Tibet yak had lower genetic diversity, which indicated that eastern Tibet may be the origin of yak. The molecular clustering relationship chart showed that Tibet 11 yak breeds or groups could be divided into two clusters. Pali Yak was a cluster, the others were another cluster. The result indicate that Tibet yak have abundant genetic diversity and significant genetic difference among the breeds or groups.