A zoom infrared imaging temperature measurement method is proposed in the context of a fixed-mounted zoom temperature measurement thermal imaging camera suitable for use in extreme weather conditions, such as high winds and high temperatures, in order to address the temperature measurement problems of a continuous zoom thermal imaging camera. Based on the engineering temperature measurement method of fixed focus thermal imagers provided in the article, the focal length dimension is expanded to construct a polynomial model for temperature measurement of zoom thermal imagers, and the inversion parameters are calculated through optimization methods to obtain temperature measurement results at different focal lengths. Furthermore, a data calibration method for zoom temperature measurement is provided. A self-developed zoom thermal imager is calibrated based on high-precision blackbody data, and the temperature measurement accuracy at different focal lengths is analyzed. Observation experiments are conducted in both laboratory and outdoor environments. The experimental results show that high-precision temperature measurement results can be obtained with different focal lengths, reaching the ±2 ℃ accuracy required by the national standard. This achievement can be promoted and applied to various types of zoom thermal imagers, improving the temperature measurement accuracy for long-distance targets such as high-voltage lines.