The power system equipment is currently facing more serious risk and threat of data leakage. The online monitoring of power transmission lines, the complexity of power consumption information collection methods and the uncontrollable operating environment make the business data of power system more prone to data leakage. On account of this, this paper firstly analyses the risk of sensitive data in power system, then studies the identification process of sensitive data in power system. The architecture and functional composition of sensitive data identification system for power system are proposed. Finally, the implementation process of sensitive data protection is given.