Abstract: According to a lot of experimental research to Cr,Tm,Ho:YAG laser operating at 2.1μm wavelength,the factors effecting on the output characteristics,such as cavity length,transparent index of output mirror,the radius of high reflectivity concave mirror and cooling temperatures,are discussed.Using the cavity with silver,whose frequency is 5Hz,the laser threshold,slope efficiency and output maximum energy are 47J,1.3% and 1.6J respectively. Meanwhile,when whose frequency is 10Hz,the laser threshold,slope efficiency and output maximum energy are 45J,1.1% and 0.97J respectively.