IR intracavity optical parametric oscillation is obtained by using an electro-optic Q-switched Nd:YAG laser as the pumping source and a 50°-cut LiNbO3 crystal as the oscillator. The wavelength is tuned by varying the temperature of LiNbO3. The tunable range is 1.47～4μm with output energy over 100μJ per pulse and linewidth less than 5cm-1. This OPO has been applied in laser chemistry with good experimental results.