The temperature is an important parameter reflected by operating condition of power network. Aimed at the puzzle of being difficulty to inspect the fault of underground cable joint, the paper explored a sort of patrol inspection system of underground cable joint fault based on wireless communication. In the paper, it analyzed the mechanism of hidden fault produced by the joint, designed the system of front end detection and background analysis and its corresponding function modules, and realized the patrol inspection for cable joint fault by means of wireless communication. The test data demonstrated that the system could realize the patrol inspection coverage over a wide area, and be used on line by networked computer. The experiment result shows that the system design is feasible and available effectively.