The characteristics of 45°-off-axially-cut and a-cut Nd:YVO4 crystal, were compared for continuous wave (CW) and passively Q-switching operations by Cr4+:YAG crystal as the intracavity saturable absorber. By analyzing the experimental results, the 45°-off-axially-cut Nd:YVO4 exhibited parts of properties of the a-cut and c-cut crystals for CW passively Q-switching operations respectively, due to the competition between π polarization and σ polarization simulated emissions. With the laser diode (LD)-pump power of 1340 mW, a peak power of 0.6- kW with a 6.5-ns pulse width and 18.7-kHz repetition rate was obtained.