The invention provides a method and a system for identifying a weak section of a power grid after anticipated multiple faults. According to a mechanism for occurrence of the multiple faults, the multiple faults are divided into a multi-loop direct-current fault, a multi-loop alternating-current fault and an alternating-current and direct-current hybrid fault from the perspective of influence on the power grid, a quantitative index transient stability limit influence factor, a static stability limit influence factor and a thermal stability limit influence factor of the influence of topologicalchanges of the multiple faults on a stability limit of a power transmission section of the power grid are provided, the active power and the stability limit of the power transmission section of the power grid after the multiple faults are determined, and a load rate of the power transmission section is computed to identify the weak section of the power grid. According to the method and the system,the influence of various types of the multiple faults on the transient stability limit, the static stability limit and the thermal stability limit of the power transmission section can be quantitatively evaluated, a rapid evaluation method for the stability limit and the load rate of the power transmission section after the multiple faults is provided, and the power transmission section of the power grid after the multiple faults can be rapidly identified.