Abstract: In order to optimize the culture method in vitro of granule cells in Tibet yak, granule cells separated from follicular fluid and mature oocytes of Tibet yak were collected to make the culture test in vitro. The results showed that the formation of mono- layers of granule cells collected from follicular fluid and mature oocytes needed 6-7 d and 5-6 d respectively during the primary culture. During the subculture, two sources of granule cells started the adherence on the second day after the inoculation, dominant growth appeared from the third day to the fifth day, and granule cells paved on the dish bottom. The results showed that the culture in vitro with the granule cells separated from mature oocytes were simple and convenient, compared with granule cells separated from follicular fluid.