The objective of this study was to evaluate the effects of rapeseed treated by high temperature and pressure on milk performance and milk fatty acids of grazing yaks. Fifteen yaks were randomly divided into the following 3 treatments: control group (group N, pasturing), low level group (group L, pasturing plus feeding 100 g/d rapeseed per yak), high level group (group H, pasturing plus feeding 200 g/d rapeseed per yak). The results showed that: (1) compared with the control group, there was no influence on milk performance and milk fatty acids by feeding 100 g/d rapeseed per yak. When the yaks were fed 200 g/d rapeseed, milk yield and content of milk components were significantly increased (P<0.05); (2) palmic aicd （C16∶0）,stearic acid （C18∶0） and oleic acid （c-9-C18∶1） were the abundant fatty acids of milk fat of grazing yaks and feeding rapeseed could significantly enhance the content of stearic acid in milk fat (P＜0.05); (3) conjugated linoleic acid (CLA) contents of milk fat were 1.23%, 1.15% and 1.18% in the control, group L and H, respectively. CLA contents and desaturase indices showed no significant difference among groups and the content of c-9,t-11-CLA in yak milk was relatively higher, which was 98.60% of the total CLA content.