The invention discloses a modeling method of a power grid system protection control strategy in online analysis. The method includes the following steps: according to a search process of a security control strategy, and in combination with a security control strategy of a regional power grid, extracting four basic elements from a power grid system: faults, power grid operating modes, power grid power flow levels, and control measures and control quantity of power grid system protection devices; defining the faults by a combination of function keywords and enumerated data types; defining the power grid operating modes by a combination of the function keywords and power grid equipment names; defining the power grid power flow levels by using power flow calculation keyword functions and the equipment names; forming the control measures and control quantity of the power grid system protection devices in power grid system protection models by using the following three elements: the controlkeywords, the equipment names and the control quantity; and performing logical configuration on the four basic elements, wherein the logical configuration is to adopt logical calculation symbols and logical judgment symbols in the C-language to perform logical configuration for strategy formulation and modeling.