The invention provides a method and a system for screening multiple faults of a power grid, comprising the steps of: acquiring data of the power grid; performing network partitioning and fault truncation according to the data of the power grid, and statistically truncating the fault order; and processing the grid fault based on the network partitioning and truncated fault order to obtain multiplefaults. The method and system provided by the invention adopt a reasonable method to partition the power grid and statistically truncate the fault order, and screen multiple faults according to the partitioning and truncated fault order, thereby overcoming the shortcoming that the prior art can only consider the first-order faults and the second-order faults of the double-circuit line, and cannotconsider the second-order combinations of all the lines and the above-mentioned order faults when calculating the large-scale power grid due to the limitation of computing power, and enabling the realization of large-scale power grid applications.