The optical properties of Nd:YVO4/YVO4 composite crystal and Nd:YVO4 single crystal were studied contrastedly in the high power laser diode-pumped solid-state lasers. It was demonstrated that the composite crystal can effectively reduce the temperature gradient of crystal, relieve the thermal lens effect and get higher output power. The frequency-doubling property of Nd:YVO4/YVO4 composite crystal with KTP was studied in a “Z-shaped” folded cavity. With the incident pump power of 17 W, 6.23 W green light was achieved with an optical conversion efficiency of 37%.