Under the current background of the ubiquitous power Internet of things and strong smart grid, high-permeability DG is an important feature of the future power energy internet, which may cause problems such as voltage over limit flicker, increased network loss, bidirectional variation of power flow, and increased grid coupling[1-2]. In this paper, the operation state interval set of power system is proposed. Considering the influence of power supply capacity on the system security boundary and stability boundary after the DG is connected to the grid, the influence of the access location of the DG on the power system power quality is qualitatively analyzed. At the same time, on the premise of satisfying the consistency of interaction information between multi-source transmission and distribution system and load[3], the problem is decomposed into the acceptance capacity of power side and the optimization planning of power side. The interval mathematics method is adopted to analyze and calculate the DG acceptance capacity of the power grid, and explores the maximum capacity of DG under the condition of safe operation of the system. It also puts forward the optimization planning method of distribution network based on the improved PSO algorithm Considering the output power interval and load level interval of distributed power supply under any possible scenario, and exploring the hybrid transmission and distribution system optimization planning method from the transmission, transmission and distribution systems. It improves the reliability and flexibility of power grid operation, and provides a theoretical basis for a large number of new energy access, and has an important guiding significance for promoting the large-scale development of new energy.