A miniature all-fiber Fabry-Perot high temperature sensor with a thin film is presented. The sensor is fabricated by splicing a hollow fiber with a grinded multimode fiber thin film on the end of a single mode fiber. The change of the optical path difference of the Fabry-Perot cavity are composed of two parts

the thermal expansion of the hollow fiber and the deflection of the thin film induced by temperature change. As the optical path difference of the sensor is langer than those of common sensors at the same temperature

it can offer a higher sensitivity. A temperature measurement experiment is carried out

results show that the sensor has a linearity of 0.996 7

sensitivity of 1.029 nm/℃ and the resolution of measuring system about 1.5 ℃.It is concluded that the miniature all-fiber Fabry-Perot high temperature sensor with a thin film will be a candidate in the field of micro-region multipoint quasi-distributed high temperature measurement.