Taking into account the time-varying coupling, we studied the dynamic model of neural oscillator in the presence of harmonic stimulus by the use of phase response curve, and derived the evolution equation of the order parameter by introducing the probability density function. Numerical simulations show that high-frequency harmonic stimulus can produce the periodically synchronized oscillations in the population of neuronal oscillators, and the period of synchronized oscillation is related to stimulus frequency. That is to say, the higher the stimulus frequency, the higher the frequency of synchronized oscillation, and the degree of synchronization increases with the increasing stimulus intensity.