The Soft Open Point (SOP) is a highly versatile, quick and precise means of controlling the power flow in distribution networks. It enables efficient balancing of load on feeders and also has the capacity for efficient fault isolation and recovery. With its advanced capabilities, the SOP helps ensure the smooth and uninterrupted operation of the power distribution system. However, due to the limitation of SOP with three-leg topology, it is difficult to solve the power supply problem when three-phase load is unbalanced. In this study, a control strategy based on the symmetrical component method is proposed for the four-legged SOP to provide a suitable current path for the management of three-phase unbalanced currents. In normal working mode, four-leg SOP can regulate the power flow and voltage distribution of the system. When one side of the distribution network is disconnected due to a fault of the system, the neutral point offset problem caused by the unbalanced three-phase load can be solved by controlling the fourth leg. The working voltage and frequency of load can be provided by SOP to achieve uninterrupted power supply of the fault side load. Finally, the simulation results have verified the power supply capability of SOP with four-leg under unbalanced load and the effectiveness and feasibility of the switching of control strategies when faults occur.