The invention relates to a power grid frequency situation on-line forecast method considering wind power and demand-side response. According to the method, the development effects of a thermal power generation unit, a wind power generation unit and demand-side response in the frequency response process of a system are comprehensively considered, a power grid frequency situation forecast polymerization model for frequency modulation by the thermal power generation unit, the wind power generation unit and the demand-side response in a combination way is built by on-line acquisition of equipmentinformation and running state information of the thermal power generation unit and the wind power generation unit in a power system, parameter setting is performed, and finally, a power grid frequencysituation on-line forecast result under a corresponding running working condition is obtained by simulation calculation on the built power grid frequency situation forecast polymerization model or according to a time domain expression obtained by deviation of the power grid frequency situation forecast polymerization model. By the design, the power grid frequency situation forecast accuracy is improved, and moreover, the frequency forecast capability of the power system is improved.