The temperature and nonlinear characteristics of Fiber Optic Gyro (FOG) are analyzed,and position and angular velocity experiments are carried out based on the temperature test system,so the effects of different temperature and angular velocity on FOG’s output can be studied. According to experimental results,temperature error model of zero bias and temperature and nonlinear error model of scale factor of FOG are built,whose parameters are estimated by using least square method. Through simulation,it is proved that the built models can reflect the temperature and nonlinear characteristics of FOG very well. Then the compensation can be done based on the models,and the accuracy of FOG can be improved greatly.