A high-rate and high-power optical parametric oscillator is experimentally demonstrated. 1064 nm Q-switched Nd:YAG laser is pumped by laser diode (LD) laser. The maximal output power is 7.8 W with the pulses repetition rate range of 5～50 kHz. Optical parametric oscillator (OPO) based on periodically-poled lithium niobate (PPMgLN) pumped by the 1064 nm Q-switched Nd:YAG laser. Periodically poled grating (Λ=30.7 μm) was successfully fabricated in 1.0 mm thick MgO:LiNbO3 (doped 5% MgO). The output infrared wavelength will change because of the expansion coefficient of PPLN material when the operating temperatures fluctuate from 40 to 200 ℃. The tuning dimensions of the infrared wavelength are 1570～1676 nm and 2942～3300 nm with the signal maximal power of 613 mW. Several hundred milliwatt of output idler average power was obtained by using short and dual-cavity, the energy of single pulse is 40 μJ, and the conversion efficiency is 3.4%.