In a control center of an interconnected power system， the measurement data is from different sources. For a conventional state estimation（SE） method， it is assumed that all elements of the measurement set are coincident and any errors introduced by transmission delays are treated as measurement errors. Significant delay time in measurement can lead to inaccurate results. To solve this problem， a time-delay compensating SE method is presented to provide better estimation results when transmission delays are serious. For measurement with small time delays， the latest data are used directly. For measurements with significant time delays， different compensating coefficients according to the delay are introduced and the measurement errors are revised using the corresponding coefficients and the measurement change between two sequential data. The test on IEEE 7-bus system shows that the new method can effectively reduce the estimation errors and yield more accurate power system states.