The invention relates to a multi-period precision measurement unit data state estimation-based bad data correction method and belongs to the power system energy management system technical field. The method includes the following steps that: state estimation is carried out with 5 minutes adopted as a period, and PMU data are scored with the result of the state estimation adopted a reference value, and the scoring results of a whole day are adopted as the scores of the PMU data, and data with a high score are adopted as credible PMU measurement; when the qualified rate of the state estimation changes abruptly, SCADA data are compared with the result of the state estimation, data which exceed a certain threshold value are adopted as bad data; and the credible PMU measurement is adopted to replace the SCADA measurement of equipment, and state estimation is carried out again, and the result of the state estimation is adopted as a final result. With the method adopted, the average qualified rate of power grid estimation and the stability of data are improved.