We demonstrated a large face pumped double-sided liquid cooling Nd:YAG slab laser. The pump light incident from the large surface of the crystal, which are cooled by high-speed flowing cooling water, while the laser beam incident on to the end face, and travels in ZigZag path along the long direction in the crystal. The flat-flat resonant cavity was built, and the output coupler transmission was 30%. The Nd:YAG slab crystal with trapezoidal shape was used as the gain medium, the size of which was 190mm×12mm×4mm, one of the surfaces of 190mm×12mm was coated with antireflection film for 808nm and another was coated with reflection film for 808nm, and the end faces of 4mm×12mm were coated with antireflection film for 1064nm, the doping concentration of Nd3+ ion was 1.0at.%. The CW LD array and QCW LD array were used as the pump source to pump the slab crystal, the light emitting surfaces of which have the same size, and the pumping light passed through the pump windows made off used silica and incident into the crystal. Under CW LD pump, the maximum of 420W laser output was gotten, and under QCW LD pump, the maximum of 502W laser out put was gotten. Due to the much higher peak power of QCW laser diode, the small-signal gain was much higher, and induced the optical efficiency of QCW pumping system was much higher, and its thermal effect was relatively smaller because of the high extraction efficiency.