The invention provides a pre-sharing-based secure data transmission method for an electric load management system, which is significant to a power load management system to resist various security threats in wireless communication environments and open Internet environments. The confidentiality, integrity and availability of transmission data of the system can be ensured through perfection of the transmission protocol identity authentication and the integrity checking mechanism of the power load management system, and encryption of important control instructions. The method has significant meaning and demonstration effects to the formulation of secure data transmission schemes for other power application systems.