A new model for optical fiber Fabry-Perot (F-P) pressure sensor with thermal stress and residual gas pressure is presented, then their impacts on thermal response of the F-P sensor are analyzed. It shows that the linear relationship between the change of cavity length and temperature has changed when thermal stress and residual gas pressure are considered. In the condition that the applying outer pressure is 100 kPa, the thermal stress plays a major influence on the sensor when the initial residual gas pressure is less than 0.87 kPa, otherwise the residual gas pressure plays the major influence on the sensor. Three kinds of optical fiber F-P sensors with different residual gas pressures are produced, then the experimental system in the temperature range from -20 ℃ to 70 ℃ is built. The result shows that the cavity length and the thermal sensitivity varying with the temperature from the experimental data agrees well with the theoretical analysis.