This paper proposes a new single-inductor multi-input multi-output (MIMO) DC-DC converter. The proposed converter allows input sources to be added or removed without affecting the input side and the output side. Meanwhile, output channels are independently controlled. The corresponding control method is the constant current control. When the constant current control is applied to all sources, the power provided by each source is proportional to the corresponding input voltage value. When the constant current control is applied to some of the input sources, the other sources can provide specific power through direct duty-cycle control. Moreover, the consideration of switching time of switches is unnecessary. Therefore, it is easy to realize the high extension capability for arbitrary inputs/outputs. A dual-input dual-output prototype is constructed to illustrate the performance of the proposed converter.