Cr,Tm,Ho:YAG laser system based on Q switching of LiNbO3 with Brewster angle cut ends is developed. The influence of the angle by which the LiNbO3 crystal is placed on the output energy and polarization properties at free running regime is measured. The experimental results indicate that when the LiNbO3 crystal is placed in the Brewster angle, the laser will achieve the highest efficiency. Furthermore, the output beam has the largest p component and the best linear polarization properties, which are beneficial to the Q switching of Cr,Tm,Ho:YAG laser. The output energy, pulse width and pulse profile of Cr,Tm,Ho:YAG laser at various lamp voltages at Q switching regime are investigated. The maximum pulse energy of 25 mJ and the minimum pulse width of 265 ns at the repetition rate of 2 Hz are achieved, and the peak power is up to 94.3 kW. The pulse profile presents nearly smooth Gaussian distribution.