The working principle and structure of the temperature detection system based on the resonator SAW sensor are presented in this paper. The key technology of the reader design in the system is described in detail. The design of RF frontend circuit in the reader is emphasized., including the hardware designs of PLL frequency synthesizer module, the transmitting circuit and the receiving circuit. At the same time, the design block diagram and workflow of the main control module of DSP is given. A detailed analysis of the test data of sensor under the environment temperature of 0~100 ℃ is carried out. The accuracy of measuring temperature is ±1 ℃. In good electromagnetic environment, the maximum temperature measurement range is up to 5 m.