Abstract: A radio frequency infrared temperature sensor suitable for underground temperature detection under complex conditions is designed. The optical system and the photo detector are used to sense the down hole temperature and extract the temperature signals in real time, and at the same time, the EMI filter is implemented in the DC-DC power supply isolation module to resist electromagnetic interference, and the processed signals are displayed after being amplified by the A/D conversion and the arithmetic unit. On the LCD, the read data is recorded on the memory chip of the sensor, and the temperature test under the mine compound disaster condition is realized, and the test precision is controlled at ±2%.