A multi-mode current-allocating device serves to control the DC to DC converter in each power supply device of a distributive power supply system. The multi-mode current-allocating device has an active current-sharing control circuit, a current-allocating bypass circuit, and a droop current sharing control circuit to be selectively operated under an active current-sharing mode, a current-allocating mode or a droop current-sharing mode according to the factors of the type of input power of each power supply device, the state of system load, and the system reliability so as to maintain the power supply efficiency of entire power supply system and reduce unnecessary power loss.