In order to improve CTH∶YAG laser output energy,the energy level transition of it is analyzed.According to CTH∶YAG laser characteristics of quasi-three-level operation,using BaSO4 pump chamber,the effects of different frequencies,cooling temperatures,output coupling mirror reflectance and different CTH∶YAG crystal profile on the output energy of laser were tested.When the water temperature is 10 ℃,the output coupling mirror reflectance is 85%,the crystal surface type is concave-concave,the power supply injected was 131J,the experimental results show that the laser energy output can reach 5.5J at 8Hz.