Abstract: The surface temperature of flame-proof electric apparatus either class I for coal mine or class II for factory apparatus is strictly limited. So how to accurately measure the surface temperature effective value of flame -proof electrical apparatus is an important standard of evaluation for the safety performance of the products. Through the analysis of several factors affecting the results of temperature measurement, the article gets the effect of numerical error on electrical surface temperature measurement under different conditions, proposes the reference suggestion on the structure type selection and the production requirements of temperature sensor and combination mode of temperature sensor and the measured object surface, which provides a reference for measuring work of the surface temperature of flame-proof electrical apparatus, and improves the scientific and the accuracy of test results, and ensures the definition of the safe use region of products.