With the increasingly serious problem of energy consumption in colleges and universities, power energy consumption management has become an important task for the sustainable development of campus. In this paper, a campus power monitoring system based on Internet of things (IoT) technology is proposed, which aims to realize the scientific management and energy-saving optimization of campus power through real-time monitoring and intelligent analysis. The system adopts the electricity monitoring node and cloud platform architecture based on edge computing, collects the key parameters of power equipment through sensors, and uses KNN algorithm to identify the type of electric appliances with high accuracy. The host computer system is designed based on Ali cloud platform, which displays the working status, power consumption trend and classification results of electric appliances in real time, and provides intuitive power usage analysis and prediction functions for campus administrators. The system test results show that the KNN algorithm has the classification accuracy of 96%–100% for a variety of electrical appliances, which can effectively support energy-saving decision-making. The system has the advantages of real-time, high accuracy and multi-parameter comprehensive analysis, which provides technical support for the construction of green campus and conservation-oriented society.