The invention provides a state estimation method and system suitable for a power distribution network. The state estimation method comprises the following steps: an intermediate state variable is introduced into a network model and a measurement equation which are constructed in advance; an estimated value of the intermediate state variable is obtained through iteration; estimated values of phaseangles of all nodes are obtained on the basis of the estimated value of the intermediate state variable, wherein the intermediate state variable comprises the square of voltage amplitudes of all the nodes and phase angle difference of the nodes at the two ends of a branch. The method and the system in the invention are suitable for the power distribution network with high impedance ratio, the algorithm convergence is good, the calculation speed is high, and the calculation precision is high.