Solenopsis invicta Buren(red imported fire ant,RIFA) was one of the most dangerous and devastating invasive pests in the world. In this paper, the changes of the activities of superoxide dismutase(SOD), catalase(CAT), peroxidase(POD), carboxylesterase(CarE) and acetylcholinestrease(AchE) in red imported fire ant workers infected by Beauveria bassiana were studied, which provided the theoretical basis for the research on red imported fire ant infected by Beauveria bassiana and the pathogenic mechanism. The results showed that the activities of SOD,CAT and POD in infected red imported fire ant workers’ bodies had changed in different degrees. 12 hours after the inoculation,the activities of SOD and CAT of infected red imported fire ant workers revealed significant difference in contrast to the untreated ones，and their enzyme activities were significantly lower than those of the controls,their POD activity was first went up and then went down; 36 hours after the inoculation,the activity of 12.33 U3 was significantly higher than that of the control group, which was 10.13 U3, but then it went down. The activity of CarE in 36 hours after inoculation was the lowest,which was 6.55 U4, greatly different from the 8.15 U4 of the control group. The activity of AchE went up at first and then went down,and reached the highest point at 9.24 U5 36 hours after the inoculation,which was significantly higher than the 6.65 U5 of the controls.