The invention discloses an island switching control method for a direct-current micro grid, comprising: in a grid-connected state, a grid-connected bidirectional converter detects the voltage value of an alternating-current grid, and an energy storing bidirectional converter detects the voltage value of a direct-current micro grid bus; when the voltage value of the alternating-current grid drops abnormally, the grid-connected bidirectional converter controls the alternating-current grid to enter a current-limiting running state; when the alternating-current grid enters the current-limiting running state and the voltage value of the direct-current micro grid bus satisfies a first island switching condition or a second island switching condition, the energy storing bidirectional converter controls an energy storing device to be switched to an island running state. The method can realize island switching control without additional components. Moreover, when the island switching control is needed, the grid-connected bidirectional converter or the energy storing bidirectional converter does not need to send the detection result to other components, but executes the switching control, so that the time is saved and the purpose of quick switching control is fulfilled. In addition, the invention further discloses an island switching control system for a direct-current micro grid.