Abstract: The distribution of temperature field has an important influence on the quality of welding of PE pipes.In this paper,the implicit finite different method is used for numerical simulation of transient temperature field in electrofusion joint for HDPE(High Density Polyethylene) pipes on the basis of the analysis on eletrofusion for PE pipes.The temperature distribution in pipes during electrofusion joining process is automatically measured with computer aided measuring system.The results show that the good agreement between the computer model and the measured temperature is obtained.So,the mathematical model founded is helpful to determine correct welding specification and to automate the electrofusion joining process.