We present a method to enhance the energy of the harmonic photon, namely using an additional half-period-delayed pulse. Because of the interference effect of two pulses, the interaction time between the external field and the atomic system is shortened. Thus, the atomic system can sustain a more intense laser pulse. It means that the actual intensity which contributes to harmonic emission will be increased. Therefore, the harmonic is extended to higher order. Our numerical simulations indicate the substantial energy increment of harmonic photons. ©1997 American Institute of Physics.