The daily inverter power supply system of ship DC network is connected with ship daily load and shore power grid through daily load converter. When the ship DC netting daily inverter power supply system is connected / disconnected from the shore power grid, it will produce impulse current and impulse voltage at the moment of connection / disconnection. Moreover, ship DC network parallel / off is a complex process with multiple operating conditions and multiple working modes. Most previous studies have not taken this into account. Only one control strategy is used in the process of parallel / off-grid, which is difficult to achieve good results. In this paper, the flexible parallel / off-grid control technology of daily inverter power supply system is studied according to various working states of daily load converter in ship DC networking. The technology adopts different control strategies in different periods to stabilize the impulse voltage and impulse current at the moment of parallel / off grid. Finally, the effectiveness of the control method is verified by building a simulation model. The simulation results show that the voltage distortion can be suppressed by adding synchronous control; The introduction of grid connected control can alleviate the impact current at the moment of grid connected. According to the different working conditions of ship docking / offshore grid connection process, synchronous control and grid connection control are adopted in time-sharing, which can realize the smooth connection / separation of DC network electric propulsion ship from shore power.