With the rapid development of renewable energy (RE) and the continuous progress of smart grid, the energy consumption characteristic design of modern power system is developing towards a more flexible and economical microgrid (MG). Meanwhile, the high participation of multi-agent integrated energy in MG brings challenges to the efficient and economic operation of the system. Aiming at the complex capacity configuration of MG with multi-functional interaction, a combined capacity optimization method for a typical independent MG including photovoltaic (PV), wind turbines (WT), diesel generators (DG) and battery energy storage system (BESS) is proposed. On the one hand, the models of PV, WT, DG, BESS and electric vechicle (EV) charging load are established. On the other hand, the EV charging load are considered, and the capacity configuration is optimized to minimize the cost, reduce greenhouse gas emissions and energy waste. The results show that the combination of PV-WT-BESS-DG is not only more reliable but also more economical. This study can provide support for the optimal allocation of MG capacity.