Soft open point（SOP） is a new kind of flexible equipment in the distribution network. Under reasonable site selection and capacity planning

it can significantly promote feeder balance

reduce transmission loss

and enhance new energy consumption

so it is crucial to carry out reasonable site selection and capacity planning for SOPs. In this paper

a three-layer planning model for the location and capacity of SOPs is proposed: the top layer determines the installation location and capacity

and passes them to the middle layer; then the middle layer uses simulated annealing algorithm to determine the operational condition of traditional regulations such as on-load tap changers（OLTC） and reactive compensation capacitors; the bottom layer solves the operation conditions of SOPs by particle swarm optimization algorithm. Furthermore

the power transmission distribution factors and incremental rate of power loss are proposed in this paper

which effectively reduce the complexity of the three-layer model. Finally

the case of IEEE33 distribution network shows that the proposed model can effectively determine the location and capacity of SOPs

and can give the joint operation conditions of SOPs and traditional regulations

which significantly reduce the operating costs of the distribution network. Therefore

it is necessary to consider the mutual coordination of SOPs and traditional regulations in order to minimize investment cost and improve operational economic benefits.