Molecular dynamics method was employed to investigate the effects of the reaction layer formed near the surface region on CF+3 etching of Si at different temperatures. The simulation results show that the coverages of F and C are sensitive to the surface temperature. With increasing temperature, the physical etching is enhanced, while the chemical etching is weakened. It is found that with increasing surface temperature, the etching rate of Si increases. As to the etching products, the yields of SiF and SiF2 increase with temperature, whereas the yield of SiF3 is not sensitive to the surface temperature. And the increase of the etching yield is mainly due to the increased desorption of SiF and SiF2. The comparison shows that the reactive layer plays an important part in the subsequeat impacting, which enhances the etching rate of Si and weakens the chemical etching intensity.