Through characteristic analysis of composite laser crystal,a thermal analysis model of rectangle composite crystal was introduced.In the thermal model,the composite crystal was characterized by axially symmetrical heating,fixed boundary temperature and coupled pump laser having Gaussian distribution.Based on the heat conductive equation and its boundary,the analytical solutions of interior temperature field and thermal deformation of YVO₄-Nd:YVO₄ composite crystal were obtained.The result shows that when the end-pumped power of diode laser is 20 W and the diameter of pump spot is 0.2 mm,the maximal temperature rise of YVO₄-Nd:YVO₄ composite crystal(the length of YVO₄ crystal is 2 mm,the length of Nd:YVO₄ crystal is 6 mm and the neodymium doped concentration in Nd:YVO₄ crystal is 0.5 %) is 324.5℃,and thermal distortion on pump-face of composite crystal is 3.61 mm.Under the same pumped conditions,the maximal temperature rise is decreased by 23.4% using the composite crystal instead of Nd:YVO₄ crystal.This means it can reduce thermal effect influence of laser crystal and improve laser characteristics and performance,and also can solve nonuniform temperature rise and thermal fracture problems of laser crystal by high power diode laser end-pumped.