In view of the inability of the traditional authenticated protocol with key agreement to meet its high real-time and low-cost practical demand because of large numbers of computations and communication interactions required by the wide coverage and enormous information of the power utilization information collecting system，a lightweight authenticated protocol with key agreement based on digital certificate and dynamic consultative mechanism of old and new parameter protection keys is presented for safe and efficient transmission of electric power data.By combining the BAN logic formalized analysis and the non-formalized analysis，it is proved that the protocol has reached level-Ⅰbelief and level-Ⅱbelief，and can realize a two-way entity authentication and perfect forward secrecy simultaneously.Also，it is capable of effectively defending various attacks and completing the real-time authentication and key agreement，meeting the demand of the power utilization information collecting system on the key application.