The formation process of the main particles in O2 plasma at different initial temperatures is numerically simulated. The changes of concentration of the various main particles at different time are tracked, and the law of influence on concentration of the main charged and of the neutral particles in plasma at the initial temperature is obtained in this paper. The calculation results show that the changing law of concentration of main particle in O2 plasma is similar with the increase of the initial temperature, but the influence on the change trends of concentration of them is not clear. With the time rising, the changes of concentration of e、O、O2、O+ are relatively evident and those of O-，O2-，O2+，O*，O2 * are relatively minor, but in the end they will come to equilibrium in state. The results are of a certain reference value to the theoretical study and practical application of plasma ignition and assisted combustion.