The invention relates to a two-stage parameter estimation method, which comprises the following steps: 1) a suspicious error parameter detection model based on an optimal measurement section is established, and suspicious error parameters in a power grid are detected; and 2) the suspicious error parameters are used as augmentation state variables, a staged augmentation state estimation model is built, and correction of suspicious error parameters is realized. Compared with the prior art, the two-stage parameter estimation method has the advantages that bad data interference is resisted, the calculation precision is high, the application prospect is broad and the like.