A type of compact temperature sensor based on microfiber knot resonator is proposed and demonstrated experimentally. The microfiber knot, which is assembled by two fiber probes, is placed on a plate glass substrate and coated with low-index polymer to keep the system robust. Sensitivities of this kind of temperature sensor as 0.27nm/°C in heating process (when temperature ranges from 28 to 140°C) and −0.28nm/°C in cooling process (when temperature ranges from 135 to 25°C) are obtained. Temperature resolution of 0.5°C is demonstrated and higher resolution is predicted with a high-resolution spectrometer.