With the increasing of distributed generation number,the development of AC/DC distribution network is unstoppable.A two-layer planning model is proposed to handle the planning problem of AC/DC distribution network.The objective functions of the first layer are system construction and operating costs.The second layer calculates the operating costs in detail by economic dispatch,which makes the result more accurate.For different bus types,branch types and network topologies,a binary coding model of AC/DC distribution network is put forward,which can be nested into intelligent algorithm conveniently.A 13-bus case study indicates that AC/DC distribution network is more economical than tradition AC distribution system in operating costs,line construction costs,VSC installation costs and generator installation costs.