The invention relates to a power grid parameter estimation method, in particular to a phase measurement unit-based power grid information graph parameter estimation method. By the method, the problem in the prior art that branch of a network parameter estimation cannot be performed if bad data, topology errors and parameter errors simultaneously exist is solved, and the requirement of configuration redundancy of a power management unit (PMU) is reduced. The method comprises the following steps of: performing topology analysis on a power grid, and determining tree lines and chord lines; calculating current information vectors of the lines with measures; calculating current information values of tree lines in each circuit to obtain the current chord line calculation information vectors of all the tree lines and the current information difference vectors of the lines with the measures; judging whether the current information difference vectors of the lines with the measures are remarkably greater or not; calculating correction prediction ratios of each line; and judging whether the correction estimated ratios of each line are greater or close to zero or not, eliminating the influence of the bad data and the topology errors according to judgment results and judging whether the lines have the parameter errors or not for parameter estimation. The method is used for the parameter estimation of the power grid.