We solve the time-dependent Schr?dinger equation in two-color laser fields by using asymptotic boundary condition and symplectic algorithm. The P?schl-Teller potential model with three bound states was considered in the numerical calculation. The population of ionization, average distance, HHG and the population of transition were calculated. We show that the efficiency of high-order harmonic generation (HHG) in two-color laser field can be enhanced, and analyze the mechanism of the enhancement of HHG. We demonstrate qualitatively the enhancement of conversion efficiency of HHG by the transition probability.