The pressure and temperature response characteristics of polymer packaged fiber Bragg grating (FBG) sensor are analyzed. The experimental results show that the pressure sensitivity is not a constant but a variable because of the effect of temperature on elastic modulus of polymer when the change range of temperature is large. The pressure sensitivity is 0.036 nm/MPa at 30℃ and 0.175 nm/MPa at 180℃ and the change of sensitivity is piecewise linear at different temperature range. So elastic modulus should be treated as the function of temperature when using polymer to packaged FBG, the pressure coefficient in the coefficient matrix of FBG should also be the function of temperature in order to eliminate the error induced by the change of elastic modulus caused by large range temperature change.