In this paper, a Mach-Zehender interference temperature sensor with high sensitivity is introduced. A section of polarization-maintaining fiber is embedded between single-mode fiber, and by overlapping extrusion discharge to form a reverse convex cone, a sensor with a structure of single mode fiber-polarization-maintaining convex cone fiber-single mode fiber is realized. The convex cone structure increases the energy of the cladding mode and improves the contrast of the transmission spectrum of the sensor. The experiments show that when the length of polarization-maintaining fiber is 2.5 cm, the maximum temperature sensitivity reaches 126.45 pm/℃ within the range of 30~70 ℃. In addition, in this paper, the main components involved in mode interference are analyzed by calculating different polarization modes and corresponding mode propagation constants, thereby verying the accuracy of temperature sensitivity measurement. The sensor with this structure has the characteristics of compact structure, small size and simple manufacturing process, which can be applied to temperature sensing measurement.