Abstract: A substation-control center tow-level distributed grid nonlinear state estimation method is provided. The method comprises steps of: collecting RTU measurement data and PMU measurement data at each voltage level in each substation; performing a first three-phase state estimation to obtain a first estimation result, and removing bad data from the RTU measurement data and the PMU measurement data to estimate a state of a CB; forming a new CB island at each voltage level, and performing a second three-phase state estimation for the new CB island to obtain a final estimation result, in which the new CB island is a bus; processing the final estimation result to obtain ripe data; and collecting the ripe data and/or a part of the RTU measurement data and a part of the PMU measurement data and performing a whole grid state estimation.