Abstract: The paper investigated the effects of adding different concentrations of undegradable fatty on MUN, NEFA,BHBA and reproduction on postpartum cows with high yield. The results showed that adding 200 g and 400g undegradable fatty could reduce the concentration of MUN, NEFA and BHBA during postpartum lactation peak, the difference was significant compared with the control, and the latter was slightly better than the former. In addition, the mean number of services and the calving to conception interval were significantly lower than those of control group (1.4±0.35 VS 2.1±0.28; 102±22.5 VS 126±23.6), and while conception rate of first service or conception rate of postnatal 100 days were obviously higher than those of control group by adding 400 g undegradable fatty after calving. So adding certain amount of undegradable fatty could reduce partly the concentration of MUN, NEFA and BHBA, and improve the reproductive performance in postpartum cows.