Peak load greatly reduces the installed utilization rate and investment benefit of power supply. The participation of virtual power plant in peak shaving can effectively delay the construction of power supply. Firstly, a fuzzy interval estimation method considering multi-domins and multiple evaluation indexes is proposed to solve the problem that the schedulable capacity of urban virtual power plants cannot be calculated accurately. This method decomposes the schedulable capacity estimation task into the fields of industry, construction and transportation, and constructs a fuzzy interval evaluation model considering user participation, revenue sensitivity, resource controllability and controllable scale. Then, based on fuzzy estimation of schedulable capacity, a power capacity planning method considering the participation of virtual power plant in peak shaving is proposed. Under the condition of meeting the power reserve capacity, the power capacity planning model is constructed by taking the minimum power expansion installation capacity as objective function, considering various factors such as different power structures, new energy output uncertainty, virtual power plant schedulable capacity, and so on. Finally,a city in East China is taken as an example to verify the effectiveness of the proposed method.