The utility model relates to a grid-connected and off-grid seamless switching control device of an energy storage converter. The grid-connected and off-grid seamless switching control device is connected with a power grid monitoring system and a grid-connected point switch, and comprises the energy storage converter, a controller, a battery management system, a battery pack and a first transformer, the controller is connected with the power grid monitoring system, the energy storage converter and the battery management system, the battery pack is connected with the energy storage converter and the battery management system, the energy storage converter is connected with a first power grid bus through the first transformer, a first interface connected with a voltage transformer, a second interface connected with the grid-connected point switch and a third interface connected with a position node of the grid-connected point switch are arranged on the controller, and the voltage transformer is arranged on the upper side of the grid-connected point switch. Compared with the prior art, the grid-connected and off-grid seamless switching control device has the advantages that the grid-connected mode can be converted into the off-grid mode with high precision at the same time, smooth grid-connected and off-grid switching is achieved, and the device does not rely on a communication network.