Abstract: In order to explore the effects of cow subclinical ketosis（SCK） on the health and production performance of dairy cows in the late perinatal period, the experiment selected 560 dairy cows in a large-scale intensive pasture in Shaanxi Province. Blood electrolytes were measured on the 1 st and 4 th day postpartum, and 60 healthy cows in the control group and 60 cows in the subclinical ketosis group were screened according to the blood ketone level on the 4 th day postpartum. Each group contained 15 cows with 1, 2, 3, and more than 3 parities（3+ parities）. The health status of dairy cows in each group within 21 days postpartum was tracked and recorded, and statistics on the incidence of postpartum cows’ true stomach displacement, retained placenta, mastitis, enteritis, foot disease and other diseases were carried out, and daily milk production on days 7, 14, and 21 postpartum; the daily milk production of each dairy cow within 305 days postpartum and the total milk production, peak day, peak milk volume, and sustainability-related lactation indicators were calculated. The number of registration days and the number of inseminations for each cow were counted. The results showed that on the first postpartum day, the serum sodium ion（Na⁺） content in the subclinical ketosis group was significantly higher than that in the control group（P＜0.05）, and the ionized calcium(iCa²⁺) content was significantly lower than that in the control group（P＜0.05）. On the 4 th postpartum day, the serum Na⁺ content in the subclinical ketosis group was higher than that in the control group, and the serum iCa²⁺ content in the subclinical ketosis group was lower than that in the control group, but the difference was not significant（P＞0.05）. The incidence rates of postpartum true stomach displacement and retained placenta in the subclinical ketosis group were significantly higher than those in the control group（P＜0.05）. On the 7 th and 14 th postpartum days, the average milk yield of the cows in the control group increased by 2.49 and 2.30 kg, respectively, compared with the subclinical ketosis group. The 305-day total lactation of cows with one parity in the subclinical ketosis group was significantly higher than that in the control group（P＜0.05）. The 305-day total lactation of multiparous cows in subclinical ketosis group（2, and more than 3+ parities） was lower than that in the control group, but the difference was not significant（P＞0.05）. High-parity dairy cows（3+ parities）, the lactation sustainability was significantly lower than that in the control group（P＜0.05）. The cows with one parity in the subclinical ketosis group had higher insemination times and registration days than those in the control group, but the difference was not significant（P＞0.05）; insemination times and the number of registration days of the cows with 2 or 3+ parities were very significantly lower than those in the control group（P＜0.01）. The results suggested that subclinical ketosis would affect the health and production performance of dairy cows, and at the same time, would increase the incidence of postpartum diseases such as true stomach displacement and retained placenta, and the effect of subclinical ketosis on total lactation was related to parity.