Abstract: This paper conducts an optimization design for off-grid PV-diesel-storage microgrid system in a commercial park in Wuhan based on HOMER software, China. Firstly, a capacity optimization planning model for the off-grid PV-diesel-storage microgrid system under multiple operation strategies is constructed. Based on this, the capacity planning of system, PV penetration ratio, and battery energy storage operational status under different operation strategies are analyzed, and the optimal operation strategy for the off-grid PVdiesel-storage microgrid system is derived. Then, the capacity optimization planning of the off-grid PV-diesel-storage microgrid under multiple scenarios is conducted based on the optimal operation strategy, and a comparative analysis of LCOE, NPC, and total emissions for the off-grid PV-diesel-storage microgrid under multiple scenarios is performed. Finally, the aout sensitivity analysis with specific cases re also carried. The results indicate that the proposed capacity planning model can achieve the best balance between economic and environmental performance of the system, and reduce the reliance on energy storage batteries. Additionally, the sensitivity analysis reveals the impact of different unit and load parameters on the optimal capacity planning.