Abstract: The objective of this study was to obtain an accurate and reliable method for determining the sex of yak embryos through amplification of SRY gene of the yaks, and evaluate embryonic development after biopsies. Two pairs of SRY gene nested primers for sex determination and two pairs of HSL gene primers as internal standard and optimized PCR reaction conditions were designed. The accuracy of PCR amplification for sex determination was verified by 24 blood samples. The result showed that in every case, the results were as expected for both female and male, i.e., accuracy was 100%. Using this optimized procedure, clear signals following PCR amplification were obtained from all samples of IVFderived yak embryos, eight cells were sampled from each embryo, 45.8% (11/24) embryos for males and 54.2% (13/24) for females. 56.7% (17/30) of biopsied embryos could further develop. It was concluded that this PCR system was highly reliable for sex determination of yak embryos.