The invention relates to an improved coordinated planning method of a medium- and low-voltage power distribution network. The improved coordinated planning method comprises the steps of proposing a coordinated planning flow of the medium- and low-voltage power distribution network according to a matching idea of power supply capability P of a medium-voltage circuit and maximum load level P of a hanging distribution transformer; calculating a comparison value of the P and the P, and estimating current power supply coordination of the medium- and low-voltage power distribution network; calling a solution scheme if a power supply coordination problem occurs in a current power grid; and proposing a new user access scheme according to a power supply margin level of the power grid, and verifying the scheme according to the comparison value of the P and the P. With the improved coordinated planning method of the medium- and low-voltage power distribution network, proposed bythe invention, the coordinated planning design of a circuit and the distribution transformer of the medium- and low-voltage power distribution network can be effectively guided, and the improvement on a planning invest benefit level of the medium- and low-voltage power distribution network is promoted.