The invention discloses a load shedding optimization model taking into consideration primary and second frequency modulation and minimum frequency deviation. Frequency deviation is added to an objective function of the optimization model, and the minimum weighted sum of the load active power reduction and the square of frequency deviation is taken as the objective function. A primary frequency modulation equation of a wind turbine unit and a secondary frequency modulation equation of an AGC unit are added to the equality constraints of the optimization model. The equality constraints of the optimization model include a frequency quality constraint, a node voltage amplitude constraint, unit active power and reactive power constraints, an AGC unit ramp constraint, a branch power constraint and a load node active power reduction constraint.