The conventional multi-terminal flexible interconnector adopts the grid-following control, which lacks grid-support capability and is prone to oscillate in a weak grid. To solve these above issues, a grid-forming control method is proposed, and the output impedance model of multi-terminal flexible interconnector is established. The interaction stability between the multi-terminal flexible interconnector and the distribution network is researched through the frequency model analysis method. Research results indicate that the grid-forming multi-terminal flexible interconnector can operate stably in both stiff and weak grids. Simulation model is established to validate the feasibility of the grid-forming control method.