Cable junction in distribution box is the weakest part of secure operation in power system, and the cable operation faults are mainly caused by junction faults. Therefore, we design a flexible and convenient cable junction monitoring system for distribution box by applying detection and communication technology etc. Through measuring some parameters of the junction, we can know the aging of insulation, correctly evaluate its working state, and find the hidden malfunctions in time, which is of much significance to enhance the reliability of the cable junction, and to reduce the occurrence and cost of faults.