Abstract: Isolates of Rhizoctonia solani, the rice sheath blight disease pathogen, were collected from rice fields in different sites before and after the applications of thifluzamide for over 3 years. And the shift of sensitivity to thifluzamide was monitored and analyzed. Meanwhile, the effect of thifluzamide on the community of natural enemies was evaluated by adopt the generally used fungicides, jinggangmycin and tebuconazole, as the pesticide control. It showed that the EC₅₀ value for the population (n=164) of R. solani collected from Zhejiang Province before thifluzamide exposure fitted unimodal distribution and varied from 0.008 to 0.135 mg/L with the mean value of (0.073±0.005) mg/L, which could be adopted as the baseline sensitivity to monitor the sensitivity shift in R. solani. The EC₅₀ value for the population (n=130) which exposed to thifluzamide for more than 3 years varied from 0.009 to 0.126 mg/L with the mean value of (0.069±0.080) mg/L. No obvious sensitivity shift of R. solani to thifluzamide was observed. Field experiments was conducted to evaluate the effect on its natural enemy’s community. The results suggested that both the Shannon diversity index and richness index, 7 days after the application of 12% thifluzamide OD in Shaoxing, were significantly higher than those of the CK. While all the above indexes obtained in other time periods or sites had no significant difference with CK. This study indicated that thifluzamide had low risk of field resistance development and is safe to the natural enemy in rice fields.