The invention discloses a medium-voltage power distribution network planning method based on a four-step grid chain, and belongs to the technical field of power distribution network planning methods,and the method comprises the following steps: S100, collecting data; S200, dividing power supply areas and power supply grids; S300, performing diagnosis according to the current situation; S400, predicting the power consumption load; S500, determining a construction target; S600, analyzing the construction target based on the four-step grid chain; S700, determining a construction scheme of the medium-voltage power distribution network; And S800, performing effect analysis. According to the medium-voltage power distribution network planning method based on the four-step grid chain provided bythe invention, the target network frame can be reasonably constructed on the basis of the block chain, the transfer and transfer capacity of a transformer substation is comprehensively improved, and the high reliability of full stop and full transfer in a test point area is favorably realized.