The temperature distribution inside the following four crystals under the working condition of end pump is simulated by using the heat conduction module in the Comsol software.The four crystals are respectively:(1)3 mm×3 mm×10 mm uniformly doped Nd∶YAG crystal;(2)3 mm×3 mm×10 mm Nd∶YAG composite crystal with 3 mm long YAG crystal bonded to two end faces;(3) 5 mm×5 mm×10 mm composite Nd∶YAG crystal with YAG crystals whose thickness is 1 mm bonded to the side;(4)5 mm×5 mm×10 mm Nd∶YAG crystal with YAG crystals whose thickness is 1 mm bonded to each of the four sides and with 3 mm long YAG crystals bonded to each of the two end faces.When the pump power is 30 W,the maximum operating temperatures of the four crystals are 153 ℃,114 ℃,157 ℃ and 115 ℃,respectively.The results show that compared with the side bonding structure,end face bonding is an effective method to reduce the operating temperature of the laser crystal and the thermal effect.In order to study the applicable conditions of the side bonding structure,the thermal conductivity of the crystal side is reduced,and under the condition of the same pump power,the maximum temperatures of the four crystals is simulated,which are 212.014 ℃,149.158 ℃,186.741 ℃and 134.410 ℃,respectively.The simulation results show that under the condition of poor heat dissipation on the side,the double bonding of the side and the end face is the best choice to reduce the thermal effect of the laser crystal.In the case of the pump power of 18W,the Nd∶YAG crystal with the YAG crystals bonded to each of sides and end faces experimentally have the highest output power of 12.1 W for the LDA pump source.The conversion efficiency can reach 67.2 %.The experimental results are consistent with the simulation results.