Sulforaphane (SFN) is a natural substance which rich in cruciferous plants and has the antioxidant effect.Based on the antioxidant system mediated by nuclear factor E2 related factor 2(Nrf2),this paper explored the effects of different time′s cold exposure on antioxidant enzymes of skeletal muscle and the effects of SFN on antioxidant capacity of skeletal muscle exposed to cold exposure.Firstly,30 male C57BL/6N mice were randomly divided into three groups,including control group (0 h group),1 hour′s cold exposure group (1 h group) and 3 hours′ cold exposure group (3 h group).Secondly,40 male C57BL/6N mice were randomly divided into 4 groups,including PBS with control group (PBS+Con),PBS with 3 hours′ cold exposure group (PBS+Cold),SFN with control group (SFN+Con),SFN with 3 hours′ cold exposure group (SFN+Cold).Mice were intraperitoneally injected with SFN or equal volume PBS four times before acute temperature intervention.After cold exposure,the skeletal muscles of mice were taken and the level of reactive oxygen species (ROS),total antioxidant capacity (T-AOC),reduced glutathione (GSH) and oxidized glutathione (GSSG) were detected by kit.The mRNA transcription of the antioxidant enzymes and enzymes related to glutathione synthesis mediated by Nrf2 were detected by RT-qPCR.The protein expression of the antioxidant enzymes mediated by Nrf2 were detected by Western blot.Compared with 0 h and 1 h group,the mRNA transcription of Nrf2 and antioxidant enzyme genes (Gpx1,Hmox1,Cat, Sod1, Nqo1) of 3 h group were significantly decreased,and the level of ROS was significantly increased.Compared with PBS+Con group,the protein expression of Nrf2 and antioxidant enzymes (HMOX1,CAT),GSH/GSSG ratio and T-AOC of PBS+Cold group were significantly decreased,while the level of GSSG and ROS were increased.Compared with PBS+Cold group,the expression of Nrf2 mRNA and its protein,the protein expression of antioxidant enzymes (HMOX1,SOD1),the mRNA transcription of antioxidant enzymes genes (Gpx1, Hmox1, Cat, Sod1, Nqo1) and enzymes genes (Gclm and Gss) involved in GSH synthesis,GSH/GSSG ratio and T-AOC level of SFN+Cold group were significantly increased,while the level of GSSG and ROS were significantly decreased.These results suggested that the 3-hour acute cold exposure reduced the antioxidant effect mediated by Nrf2.When SFN was given before acute cold exposure,the antioxidant enzymes and glutathione antioxidant system mediated by Nrf2 were activated,and then the antioxidant capacity of skeletal muscle was enhanced.