To further study the reacting mechanism of cornstalks conversion to sugar in a plasma reaction,we study the active particles distribution of cornstalk reacting in the N2/H2O discharge gas.By statistical mechanics and statistical thermodynamics theories,we analyze that the ionization of the mixed discharging gas in plasma reactor and the active particlesdistribute variances with temperature;deduce the constant pressure form of Saha equation suit for this experiment;analyze the active particles in the strong ionization discharging process and the cornstalk inverting process in the plasma reactor.The results show that the discharging gas,N2 and H2O can ionize at the same time in the given experimental conditions.