A tapered double-cladding fiber (TDCF) temperature sensor based on surface temperature sensitive thin-film is presented. It consists of two sections of common single-mode fiber (SMF), and a TDCF is welded between them. The structure is SMF-TDCF-SMF. Because the mode field of the SMF core mode does not match that of the TDCF core mode, the light transmitted from SMF is partially coupled into the TDCF core, and the rest is coupled into the TDCF cladding in the form of a cladding mode. When the two beams reach output end SMF and interfere, the Mach-Zehnder interferometer can be obtained. The TDCF is coated with a layer of temperature-sensitive thin-film, so that the optical path difference between the TDCF core mode and the cladding mode will change with the external temperature, thus causing a change in the sensor interference spectrum. Therefore, temperature measurement can be achieved by detecting changes in the sensing spectrum. The temperature characteristics of the sensor are experimentally studied, and the results show that the free spectral range of the sensor decreases with the increase of tapered cone length. When the length of the tapered cone is 16 mm and the temperature is within the range of 32-65.3 ℃, the transmission spectrum of the sensor is blue-shifted with the increase of temperature. The temperature sensitivity is up to -1296.78 pm/℃, and it has good linearity degree. The sensor is simple, highly sensitive, and has good prospects in temperature measurement occasions of scientific research, industrial and agricultural production.