The output characteristics of an acoustic-optic (AO) Q-switched laser diode (LD) stacks partially end-pumped Nd:YVO4 slab laser was demonstrated. A stable cavity was employed,the curvature radius of input mirror was 500 mm,the transmission of the output mirror was 35%,and the cavity length is 110 mm. The size of the 0.3% Nd:YVO4 slab crystal was 12 mm×10 mm×1 mm,with a-cut and the c-axis along its 12 mm-direction. At pumping power of 104 W and repetition rate of 40 kHz,the average output power of 40 W and single pulse energy of 1 mJ were achieved with an optical-to-optical efficiency of 38.4% and pulse width of 42.2 ns;at repetition rate of 20 kHz,the average output power of 33.3 W and single pulse energy of 1.66 mJ were achieved with the pulse width of 21.1 ns.