Abstract: Three-phase load unbalance mitigation is conducive to solving the problems of high line loss and poor power supply quality in the low-voltage distribution station area. It is significant for improving the economic operation level of the station area.Besides, the installation and application of automatic phase commutation devices for the low-voltage load make the three-phase unbalance mitigation of the station area more flexible. In this background, a siting and sizing planning of automatic phase commutation devices is proposed for three-phase unbalance mitigation in the station area. Firstly, the three-phase unbalance mitigation mode of the station area based on automatic phase commutation devices is analyzed. The users participating in the threephase unbalance mitigation are divided and the three-phase unbalance degree is defined. Then, a planning model for the siting and sizing of automatic phase commutation devices is proposed to minimize the sum of the construction cost of the commutation device system and the total operation cost in all the scenarios, so as to obtain the optimal siting and sizing of the devices. Finally, the validity of the proposed model is verified by taking a low-voltage station area as an example.