The invention relates to a state estimation method of an active power distribution network based on multi-sampling-period mixed measurement. The state estimation method comprises the steps of 1) judging whether a sampling moment of AMI reaches or not, if so, forming RTU, PMU and AMI into mixed measurement, and turning to a next step; or otherwise, forming a linear dynamic state estimation prediction result of the last moment, the RTU and PMU into mixed measurement, and judging whether a nonlinear static state estimation starting moment reaches or not, if so, turning to the second step, or otherwise, turning to the third step; performing nonlinear static state estimation, and turning to the fourth step; judging whether a linear static state estimation starting moment reaches or not, if so, performing linear static state estimation, or otherwise, continuously waiting until the linear static state estimation starting moment is reached, and after completing the linear static state estimation, turning to the fourth step; performing state filtering calculation of the linear dynamic state estimation of the active power distribution network based on node injection power; and performing state prediction calculation. The nonlinear static state estimation period can be shortened while the nonlinear static state estimation accuracy can be improved.