Because of the continuous expansion of modern power systems， ever increasing computation and data processing capabilities are demanded for power system analysis. The existing computing platform of power systems， however， cannot meet these computational requirements. Given this background， an advanced power system computing platform based on cloud computing is developed. The basic concepts and main technical characteristics of cloud computing are introduced first. The cloud computing is then comprehensively compared with another large-scale distributed computing technology， namely grid computing. From aspects of the hardware components， system architecture and software technology， the implementation of power system cloud computing is presented in details. The potential applications of cloud computing in a number of areas， including power system security assessment， power flow and optimal power flow computation， system restoration， system monitoring and control， scheduling and reliability assessment， are clarified. Several important research problems to be resolved are finally discussed.