In this paper, a kind of high temperature pressure sensor based on fiber grating (FBG) is designed to meet the demand of pressure detection. Through analysis and comparison, suitable packaging materials and grating coating layers were selected, structural parameters were designed, and a three-dimensional model of the sensor packaging structure was established by finite element method (Ansys Workbench). The simulation of the model was realized by applying load. The simulation results verify the rationality of the design of the pressure transfer structure of the sensor. At the same time, based on the small deflection deformation theory of thin plate, the pressure sensitivity of the sensor is calculated, the temperature compensation method of the sensor is designed, the pressure and temperature calibration experiments are carried out, the pressure sensitivity of the sensor at different temperatures is analyzed, and the effectiveness of the sensor pressure measurement and temperature compensation method at 100~450 ℃ is proved.