Abstract: The thermal design of the solid-state laser pumped by the diode array is studied in the article. By using the method of calculating thermal resistance, thermal electronic controller and corresponding heat sink have been selected according to the power of the diode array. We obtain precise temperature control of the diode array pumped solid-state laser by using forced cooling. The output energy of the Laser is 80 mJ in the repetition of 25 Hz. The results show that the laser has stable performances and meets the requirements in the ambient temperature of 40 degrees below zero to 55 degrees.