Innovative experimental teaching aids have good practicability, but complex experimental improvement schemes will make students have a sense of fear and distance to experimental instruments. Therefore, teachers should try to make experimental equipment live. In the epidemic situation, it is found that the surface mode of infrared electron thermometer can directly measure the solid surface temperature. Inspired by this, the infrared electronic thermometer is used to replace the traditional thermometer, which successfully breaks through the problem that the traditional thermometer cannot directly measure the solid surface temperature and the temperature of the left and right resistors in the traditional experiment is difficult to read at the same time, and provides another reference scheme for the experimental teaching of Joule's law.