A fiber-coupled laser-diode end-pumped passively Q-switched Nd:YVO4 laser with a Cr4 + :YAG saturable absorber is realized, providing pulse widths of 107 to 240 ns with pulse repetition rates ranging from 60 to 150 KHz. The dependences of pulsewidth, pulse energy, pulse repetition rate, and peak power on pump power are measured; meanwhile, the influences of different small-signal transmission T0 of a saturable absorber on Q-switched performances is compared. The rate equations are used to simulate the Q-switched process of the laser. The modified Q-switched criterion including the influence of pump power of this type laser is presented. The experimental results agree with the numerical solutions of the rate equations.