A widely tunable quasi-phase-matched optical parametric oscillator that uses periodically poled LiNbO 3 with a multigrating structure is reported in this paper. With a 1064 nm acousto-optically Q-switched Nd∶YVO 4 pump laser, a tunable IR output from 1.436 μm to 1.7 μm is obtained. The threshold is 10.3 μJ with pulses repetition rate 10 kHz. The maximum output energy of signal is 4.25 μJ with the conversion efficience of 12.5%.