Based on nematic liquid crystal (NLC) and multimode interference princ iple,a novel all-fiber temperature sensor is proposed.A piece of no-core fiber (NCF) with a large dia meter of 200μm and 10cm in length is spliced between two single-mode fibers to form a single mod e (SM)-no core (NC)-SM structure.As the micro-structure is sealed in an NLC-filled capillary with glu e,the compact temperature sensing probe is fabricated.The liquid crystal can be considered as the clad ding of NC fiber.Based on the extraordinarily large thermo-optic coefficient (dn/ dT) of NLC and tunable refractive index of NLC with the temperature,the light which can pass through the SM-NC-SM structure is modulated by temperature.And by measuring the wavelength shift of the peak, the environmental temperature detection can be achieved with the high sensitivity of 626.6pm/℃ in a temperature range of 27－67℃. We have also built the corresponding photoelectric system to convert t he detection of wavelength shifts into the voltage size measurement,and t he relative error is less than 4%.Given the nature of simplicity,low cost and high sensitivity,the presented fiber sensor with NLC- filled SM-NC-SM structure provides the potential to temperature sensing applications.