The terahertz frequency band is located between the microwave and infrared bands in the electromagnetic spectrum. Compared with infrared radiation, terahertz radiation can transmit through most common clothing. A passive terahertz imager with a high spatial resolution is used to measure the whole-body temperature by our team. The calibration result of the temperature is provided, which shows that the temperature measurement error of our system is about ±0.7 K. More than 90 colleagues’ terahertz images and raw data were collected by our imager. The measured temperatures of forehead and palm of hand collected by our terahertz imager and an infrared camera are provided. The influence of clothing is also researched in our experiment.