The invention provides an optical fiber Fabry-Perot temperature sensor, which comprises a temperature sensing core body 7, an optical fiber inserting core 8 and a multimode optical fiber 9, and is characterized in that the multimode optical fiber is inserted and fixed in a hole of the optical fiber inserting core, and the end face of the optical fiber is flush with the end face of the optical fiber inserting core; the temperature sensing core body is assembled at the end face of the optical fiber inserting core and is connected with the optical fiber inserting core, the temperature sensing core body is provided with a temperature cavity packaged with certain gas and a vacuum Fabry-Perot cavity 4 which are separated by a silicon wafer 3, the pressure difference of two sides of the silicon wafer 3 is equal to gas pressure P in the temperature cavity 2, and the cavity length y of the Fabry-Perot cavity 4 is in direct proportion to the gas pressure P in the temperature cavity 2; when the gas in the temperature cavity is affected by the temperature and has thermal expansion, the gas state varies along with the temperature, the pressure difference of the two sides of the silicon wafer is changed, the silicon wafer is deformed, a pressure temperature value of the gas in the temperature cavity 2 is converted into a Fabry-Perot cavity length value capable of being directly measured by the Fabry-Perot cavity 4, and the deformation quantity of the silicon wafer is detected through a Fabry-Perot interference principle so as to realize temperature detection.