Abstract: 34 serums of yak with IBRV（ positive group） and 18 serums of health （negetive group） were detected liver function indexes by mean of boichemistry. The results were showed that: The total protein, globin, βglobin of positive serum were lower than those of negative serum (P<0.05), but AST, ALT and AST/ALT of positive serum were higher than those of negative serum ,there was very significant difference (P<0.01), there were not statistical value between others indexes of positive serum and ones of negative serum（P>0.05），and livers of part yaks with IBRV were damagede heavily（11.77%）.

Key words: Yak; IBRV; liver function