The present invention provides a multi-DC receiving terminal power grid integrated load optimization control method and system which are suitable for integrated load control of large-scale receiving terminal power grid DC locking faults. The method based on the safe and stable control policy of a power grid, comprises the steps of: calculating specific load control quantity of each substation, determining the minimum comprehensive load shedding capacity which can maintain the safety and stability of the multi-DC receiving terminal power grid system by employing the improved particle swarm optimization algorithm, and executing the load shedding operation according to the minimum comprehensive load shedding capacity. The integrated load optimization control method and the corresponding control system disclosed in the invention take the safe and stable control of the large-scale receiving terminal power grid as a target to lay a foundation for optimizing the installation of the power gridload-cutting device, improving the economical operation of the system, and ensuring the safety and stability of the system.