A power distribution network load flow calculation method considering space-time characteristics of a distributed power supply adopts a forward-backward sweep method and comprises the following steps:assuming that each node voltage is a root node voltage, and calculating the current of each branch or the starting end power of each branch to the starting end of a radiation network from a tail endnode according to the known load power of each node and each node voltage; and then calculating the voltage of each node to the tail end according to the voltage of the root node and the obtained current of each branch or the starting end power of each branch, and repeating the above processes until iteration is completed. According to the invention, the limitation of traditional power distribution network load flow calculation can be improved; the method can be used for evaluating the influence of the connected distributed power supply in the active power distribution network on the power distribution system, can also analyze the influence of the distributed power supply on the static stability of the power grid, and is the basis of other theoretical research work, and the forward-backward sweep method has the characteristics of good convergence, high calculation speed and simple programming, and has very strong practicability.