Currently, the massive renewable energy generation (REG) integration into the power grid changes it from synchronous generator-based to inverter-based, leading to the inertia of the power grid under a gradual decrease. The energy storage (ES) with fast power response and bi-directional power process ability can be used for supporting the power grid’s stable operation when the power grid with a high proportion REG. Especially for the grid-forming ES inverter (ESI), which can further increase the capability of frequency and voltage support in a weak grid. However, the verification method for the ESI control method’s reliability and effectiveness is usually through the simulation or hardware test, which is not accurate, long time-consuming, or expensive for the large capacity ESI. Therefore, in this paper, an experimental platform that uses the hardware in the loop (HIL) strategy through real-time digital simulators (RTDS) and digital signal processing (DSP) for real control is built, which can significantly increase verification speed and reduce cost.