Abstract: Torrefaction atmosphere is one of the key problems in industrial application of torrefaction technology. In this paper, the effects of oxygen concentration and torrefaction temperature on the physicochemical properties of rice straw during oxidative torrefaction were investigated by simulating the atmosphere of oxy-fuel combustion flue gas. The results show that the effect of temperature on oxidative torrefaction is more significant compared with oxygen concentration. At low temperature (< 250 ℃), oxygen concentration has little effect on the mass and energy yield of torrefied rice straw, but it has obvious effect at high temperature (> 250 ℃). With the increase of temperature (> 250 ℃), the mass and energy yields of torrefied rice straw decrease significantly. When the temperature and oxygen concentration are 250 ℃ and 6%, respectively, it is a suitable oxidative torrefaction condition. Under this condition, the mass and energy yields of torrefied rice straw can be maintained above 70% and 80%, respectively. Increasing the temperature mainly enhances the torrefaction reaction, and the oxidation reaction has an obvious effect when the oxygen concentration exceeds 6%. The retention ratio of chlorine and potassium has an downward trend with the increase of temperature and oxygen concentration, and the effect of increasing temperature is more significant.