A forced vibration system will approach its maximum vibration amplitude at resonance, if the resonant frequency has to be passed. This peak amplitude can be reduced by means of phase modulation technique, whose mechanism is that the increase/decrease of vibration amplitude is closely related to the phase difference between the response and excitement, and the phase difference can be modulated by controlling the course of excitement frequency. Experimental verification was conducted with a cantilever beam subjected to pulses excitement. For the given maximum rate of increasing the excitement frequency, the maximum vibration amplitude of the cantilever was reduced about 18 % with phase modulating during the passage of the first resonant frequency.