In order to solve nonlinear and unstable problem in measurement, a fiber-optic temperature sensing film probe was designed. The material of the sensing film probe is germanium. The sensing probe is a double-layered film structure, in which the low refractive index material is silicon dioxide and the high refractive index material is germanium. The detection principle is based on the changes of refractive index of germanium because of the temperature change, resulting in changes in the reflectivity. Practically, we can get the temperature figures by measuring the reflected power. The line linearization of the sensor, which was obtained over a temperature measurement range of 30 ℃~130 ℃ is 99.85%. The results show that the conclusion can meet the purpose of linearization of fiber temperature sensor.