The effects of oxygen supply and illumination, initial concentration of HMX, inoculation quantity, pH value and temperature on the degradation ability of HMX by domesticated Rhodobacter sphaeroides H strain were studied. Its kinetic equation of degradation was fitted and analyzed. The optimum conditions for the degradation of HMX by Rhodobacter sphaeroides were determined by changing one influencing factor and fixing the other four conditions. The concentration of HMX and the cell amount of Rhodobacter sphaeroides were measured by a spectrophotometer. The results show that domesticated Rhodobacter sphaeroides can efficiently degrade HMX, Rhodobacter sphaeroides H strain can grow commendably and degrade HMX under different conditions of oxygen supply and illumination, and the degradation rate reaches more than 70%. The best degradation condition is anaerobic illumination. The optimum conditions for the degradation of HMX are initial concentration of 100 mg·L^-1, pH=7, inoculation quantity of 15% and temperature of 30 ℃, the degradation rate of HMX is the highest, reaching 88.9%. The degradation process of HMX by Rhodobacter sphaeroides is consistent with the first order kinetic equation.