Many new challenges are brought to the modern power grid from the rapid and large-scale development of renewable energy. In particular, the high penetration of power electronic interface brings security risks to the stability operation of the modern power system. The grid simulator can generate various operating scenarios to test grid-connected power generation equipment. In this paper, a high-performance modular multilevel grid simulator and corresponding control strategy are presented. The system consists of three-phase independent power converters, which including uniform power modules to achieve medium/high voltage. Each power module owns an active front end (AFE) rectifier and H-bridge converter sharing a common dc-bus. The model predictive control (MPC) is implemented to obtain the high-quality, fast and accurate output voltage. Model reference adaptive control (MRAC) is added in MPC to estimate the inductance value and improve system robustness. The simulation results show that the elaborated grid simulator can obtain the voltage transient, frequency fluctuation, waveform distortion and malfunctions effectively and accurately.