The present invention discloses a slope control device capable of predicting uniform-current-sharing level and method thereof which can be applied in a redundancy or distributed power system for providing better uniform-current-sharing ability. The device comprises a high linearity transconductor circuit, a slope adjusting circuit and an incremental output voltage circuit. The invention applies either a transconductor parameter or a feedback resistor to increase the droop gain and therefore the current deviation between two power supply modules is reduced. The invention further raises the output voltage step by step to ensure that the output voltage meet the requirement of allowable minimum output voltage according to increment of load current.