After domestication of wild yak and utilization of its frozen semen was successful in 1983, frozen semen of wild yak was used to improve domestic yak and local yellow cattle by artificial insemination(AI). Hybrid vigor of their F1 was obvious, i. e. , productive performance of F1 was significantly increased. Their offspring did not only have significant heterosis in performance but also can rejuvenate effectively their adaptability and survival, and can use alpine grassland more efficiently. This resulted in significant social and economic benefits.Compared with dairy cattle, beef cattle and yellow cattle, AI of yak was more difficult. Using AI to improve yak performance was difficult and significant in yak production areas of our country. It is necessary to invest more technique and fund to extend AI.