The invention discloses a method for calculating cooperative 
power flow of an active power distribution network and a 
power transmission network based on a 
system of systems (SoS). The method comprises the steps of defining an 
electric power system to be the SoS, and building an SoS model; modeling the 
power transmission network and the active power distribution network to be two independent systems in the whole 
system; considering the relation between a 
distributed power supply and a load in the active power distribution network, and determining an operating state of the active power distribution network; respectively considering 
power flow calculation of the active power 
distribution system and the 
power transmission network system according to different operating states of the active power distribution network; taking boundary calculation results of the two systems as initial values of each iteration thereof until the boundary results converge, and acquiring a 
power flow calculation result of the whole 
electric power system. According to the invention, the SoS model for power flow calculation of the 
electric power system is built, the power 
transmission network and the active power distribution network are modeled to be two independent systems, and 
voltage and power of only boundary nodes are required to be interacted, so that complex power flow calculation of the 
electric power system is enabled to be simplified. In addition, 
distributed management is easy to be performed, and a certain basis is laid for optimization of a distributed 
electric power system.