Aiming at the problem that the temperature measurement accuracy of the online infrared thermometer is easily affected by the environmental temperature, which causes big measurement error, an infrared temperature measurement compensation method based on the environmental temperature is proposed to improve the measurement accuracy. First, based on the principle of infrared temperature measurement, an infrared temperature measurement experiment platform was built, and temperature measurement data under different ambient temperatures were obtained. Then, using the principle of least square method to fit the extracted mean value of temperature measurement error to the curve of error-ambient temperature, the infrared temperature measurement compensation model was obtained. Finally, experiments were carried out to verify. The results show that using the compensation model to compensate the infrared temperature measurement data, the maximum relative error between the infrared temperature measurement value and the true temperature value of the measured target is 0.29%. It shows that the compensation method effectively reduces the measurement error of the infrared temperature measurement system caused by environmental temperature changes, and improves the measurement accuracy.