In order to meet the pressure measurement requirements in high temperature environments, a high temperature F-P（Fabry-Perot） optical fiber pressure sensor based on CO2 laser welding was developed. The manufacturing process of the MEMS（Micro Electro Mechanical Systems）pressure sensitive structure was introduced, the welding process between the sensor components was studied, and the no-adhesive packaging of the high temperature F-P optical fiber pressure sensor was achieved. On this basis, the temperature characteristics and high temperature pressure performance of the sensor were studied. The research results showed that the sensor packaged by CO2 laser welding has high reliability，and the sensor signal was transmitted normally at high temperature with no spectral energy attenuation phenomenon. In the environment of 300℃, the measurement error of the sensor in the pressure range of (0~2.5) MPa was less than 0.2% FS, which realized the accurate measurement of high temperature pressure. However, the influence of temperature on the sensor cannot be ignored, and the sensor needs to be temperature compensated in the application.