The distributed static series compensator (DSSC) has the characteristics of small size and low power consumption, and it can be directly connected to the power line for power flow control which makes it become one of the most promising distributed flexible AC transmission technologies. In order to solve the problem of coordinated coordination control of each sub-module in the DSSC system, the paper discusses the difference between the operating state and the adjustment performance of each sub-module, and proposes real-time optimization allocation method on the output of sub-module according to the idea of “classifying with state-setting performance with adjustment performance”, to achieve the minimum number of start-stop sub-modules and to extend the operating life of the sub-module. Based on the RTDS platform, the closed-loop simulation analysis of the optimized allocation method is carried out. It is verified that the method can meet the power flow control requirements of DSSC. Compared with the traditional average distribution method and the proportional distribution method, the method has greatly improved the adjustment speed and adjustment accuracy.