The millisecond precision load control system transforms the load-shedding control mode from the traditional centralized power cut-off of the substation load lines to the fast and accurate control of the user-interruptible branch load-carrying lines.Based on the analysis of the existing terminal access communication technology,the overall structure of the system is proposed,which consists of the control master station layer,the control sub station layer and the end user access layer,describes the function definition of each level,and also gives the overall minimum-cut control strategy in consideration of the DC fault position and the load stratification.The key technologies needed in the system implementation are introduced in detail:the STM-1 communication interface technology,the 2M channel access technology of multiuser sharing,the test technology of simulating the mass resection of large-scale interruptible load and the sequential recovery.The technical scheme proposed in this paper has been applied in the first and second phase project of the precise load shedding in Jiangsu Power Grid,and the field test shows that it satisfies the running requirements.