The diode laser side-dumped 100 Hz E-O Q-switch TEM00-mode laser is studied. The pump source was a quasi-CW 100 W diode laser array. A eylindrical lens was used as a coupler between the diode laser and the Nd:YAG thin slab with the trapezoidal section. The laser resonator is a plane-concave cavity with a curvature radius of 3 m. Using KD*P Pockels cell, the laser produced 2.37-mJ/pulse, 7-ns pulse width, M2=1.1 beam quality and 100 Hz pulse repetition rates. Optics-opties efficiency and slope efficiency of the Q-switch laser were 8.5% and 18.9%, respectively.