An electro optically cavity-dumped laser diode-pumped mode-locked Nd∶YAG laser with a semiconductor saturable absorber mirror is reported. In the experiment tha authors employed a simple straight cavity to study the cavity dumping of the mode-locked laser. The generation, amplification and dumping of the short pulses were completed in this simple setup. With 5 W pump power the authors obtained the 11 ps single mode-locked pulse output and 200 ns Q-switched pulse output, and the single pulse energy is 30 nJ and the repetition rate is 10 Hz. The single pulse energy of cavity dumped pulse is about 15 times that of the continuous mode-locked pulse. The effect of the high voltage on the electro optical crystal and the polarization of polariser on the mode-locked pulse and the Q-switched pulse are discussed.