Abstract: Most of the traditional synchronverters adopt off-grid operation to deal with instantaneous inrush current impact during grid failure, taking no consideration of the potential hazards to inverter itself or to the public power grid. Therefore, it is very important to study a method of instantaneous inrush current suppression for synchronverter. Firstly, the basic characteristics of synchronverters were analyzed. The results show that there will be large inrush current at the synchronverter’s output port when the grid faults happen due to the non-mutable fundamental voltage outputted by the inverter. This will take a great threat to the safe and reliable operation of power electronic devices and the stability of the public grid. Based on this, a new restraining strategy was proposed in this paper, in which the synchronverter switches to quasi-proportional resonant（Quasi-PR） control mode during grid fault and smoothly switches back to the virtual synchronous mode after the fault cleared. It can quickly suppress the instantaneous inrush current and support the restoration of grid voltage while maintaining the inverter operating on grid-connected mode. Simulation and experiment results verified the correctness and validity of the proposed method.