[Objective] To investigate the relationship between perinatal diseases and contents of superoxide dismutase (SOD) and malondialdehyde (MDA) in serum of dairy cows. [Method] A total of 38 dairy cows including 22 healthy cows, five cows with ketosis, four cows with fatty liver and seven cows with retained fatal placenta in perinatal period were selected. The contents of SOD and MDA in serum were respectively determined at different times ante partum and post partum. [Result] In the dairy cows with perinatal diseases, the SOD activity is lower and the MDA content was higher than that in the healthy dairy cows during perinatal period. [Conclusion] The antioxidant activity of dairy cows with perinatal diseases is lower than that of healthy dairy cows during perinatal period. [Objective] To investigate the relationship between perinatal diseases and contents of superoxide dismutase (SOD) and malondialdehyde (MDA) in serum of dairy cows. [Method] A total of 38 dairy cows including 22 healthy cows, five cows with ketosis, four cows with fatty liver and seven cows with retained fatal placenta in perinatal period were selected. The contents of SOD and MDA in serum were determined determined at different times ante partum and post part. [Result] In the dairy cows with perinatal diseases, the SOD activity is lower and the MDA content was higher than that in the the healthy dairy cows during perinatal period. [Conclusion] The antioxidant activity of dairy cows with perinatal diseases is lower than that of healthy dairy cows during perinatal period.