Aiming at the characteristics of high speed for Q-switch, a novel design method of high speed Q-switch drive circuit based on Marx generator was proposed. The high pressure module was used to generate high voltage to charge the capacitors in parallel, and the transformer was used to drive 8 MOS transistors. When the trigger signal arrived, meanwhile the capacitors discharge in series as the MOS transistors were in ON-state, so that a higher voltage pulse can be obtained as the voltage multiplier. Experiment results show that the rise time of Q-switch pulse is about 12 ns, voltage magnitude is 3 000-4 000 V. Compared to the wave of traditional pulse transformer, the rise time minish 35 ns.The Q-switched module has already been used in the laser diode (LD) pumped solid Nd: YAG laser, and it works steadily and chronically.