The aggregation form of DERs inside VPP has impact on its output stability and efficiency of each DER. An internal resource aggregation strategy of VPP based on different basic configurations is proposed according to VPP’s preferences for different DERs. Firstly, characteristics of DERs are described. Then an aggregation model of internal resources, which takes into account the operational characteristics of DERs and constraints of power system, is established aiming at maximizing the VPP’s profit in the dayahead market. Multiscenario method is used to deal with uncertainty of DERs. The combination form of VPP’s internal resources and output of each DER in different scenarios are derived from the model. The results of case study show that the combination form of DERs varies with the change of operation scenarios. There is a significant demand for the flexible DERs in every kind of scenario. Meanwhile,comparing with others, VPP with flexible DERs as basic configuration can obtain a larger profit.