Under the background of energy conservation and emission reduction, the active distribution network with large amount of distributed power has become the mainstream at present. In view of the theme that incremental distribution network investment by social capital, considering the current development requirements of distribution network and power market environment, integrating active operation mode and demand response mechanism, an investment and operation two-layer scene planning model was established.The upper layer is solved through the Parceno-Genetic Algorithm(PGA) encoded by the tree structure and the lower layer finds the solution by the primal-dual interior point method. Finally, the optimal investment decision-making scheme of the incremental distribution network is obtained.The results show that the introduction of the market mechanism as well as the optimization of the active elements such as adjustable load and distributed power can optimize the investment and operation costs of the incremental distribution network while effectively improving the profitability level, and realize the maximization of economic benefits while ensuring the safety and stability of the system.