With p-nitrophenol (PNP) as the target pollutant, the degradation characteristics of PNP by Rhodobacter sphaeroides H strain were studied. The degradation conditions were optimized by single factor test and response surface analysis, and the degradation ability of H strain to PNP was improved. Different reaction systems have been set up to prove that H strain living cells are the main body of degrading PNP, and can degrade PNP under anaerobic light, anaerobic darkness, aerobic light and aerobic darkness. The single factor experiments show that the significant influencing factors are initial concentration of PNP, pH value and temperature. The optimal degradation conditions after response surface optimization are: initial concentration of PNP is 81.01 mg·L^-1, pH value is 8.09 and temperature is 30.49 ℃. The predicted value of PNP degradation rate is 92.3%, which is 1.2%(<2%) different from the actual value(91.1%). Under the optimum conditions, the relationship between the growth of H strain and the concentration of PNP with time shows that the concentration of PNP decreased from 81.01 mg·L^-1 to 20.33 mg·L^-1 within 96 hours of the growth adaptation period of H strain, and the corresponding degradation rate is 74.9%. Then, in the exponential growth period of 96-168 hours, PNP is rapidly degraded, and the degradation rate reaches 91.1%. At the same time, the first-order kinetic equation of PNP degradation of H strain under this condition was fitted.