A comprehensive experimental study of the prepumping technology on the passively Q-switched monolithic Cr4+, Nd:YAG laser is presented. Compared with pulse pumping, the stability of pulse energy and the temporal jitter of laser pulses are improved to a great extent with prepumping modulation. The dependency of output stability performance on the four prepumping parameters is shown. Among them the base current Ib plays an important role. The dynamic of the prepumping is given. The experimental results show that prepumping is a promising method to get stabilized Q-switch pulse in miniature Nd:YAG laser.