Theoretical and experimental study is presented on near infrared band tuning and output characteristics of optical parametric oscillator based on periodically poled MgO:LiNbO3 (PPMgLN-OPO). The temperature tuning curve of PPMgLN is calculated. Through OPO experiments based on PPMgLN pumped by a 1.064 μm Nd:YVO4 laser, we realize tunable infrared laser output of 1.8~2.6 μm. We also compare the output characteristics of length of 2 cm and 3 cm PPMgLN crystals. When the pump power is 6.7 W, up to 3.2 W laser output in the 2 μm band is generated with a conversion efficiency of 47.8%.