To further investigate the red band of Nd∶YAG ceramic laser, an electro-optical Q-switched ceramic laser at the wavelength of 670 nm was studied. The Nd∶YAG ceramic crystal with 1.1at% Nd doping and dimensions of Φ3×50 mm2 was side-pumped by three laser diodes positioned with 120° respectively. The folding cavity parameters based on the ceramic thermal focal length were designed. The influences of thermal focal length in ceramic crystal and frequency crystal on spot radius were discussed. The LN crystal to electro-optical Q-switched and KTP crystal typeⅡphase matching for intracavity frequency-doubling were used to realize the laser. Under repetition rate of 1 000 Hz and single pulse pumped energy of 144 mJ, the output energy of 1.48 mJ and pulse width of 35 ns were obtained at 670 nm, and the optic-optic efficiency was 1.03%.