Based on the concept of uncertainty of measurement， this paper proposes a novel three-phase distribution state estimating method， which takes the maximum of the number of normal measuring points as the objective. As the distribution network has such peculiar characteristics as being three-phase unbalanced， radial， large-scale， frequent current measurements， difficult numerical calculation， etc， this method chooses the real and imaginary parts of branch current and node voltage as the state variables. By testing on IEEE 13-bus， IEEE 37-bus， IEEE 123-bus systems， this method is proved to have the advantages of strong anti-error property， fast convergence and good rationality， etc. This method has a good prospect of online application.