The invention discloses an over-current protection method. A device for implementing the method comprises a current sampling and converting unit, a current comparing unit, a protection acting unit and an over-current threshold value operating unit, wherein the over-current threshold value operating unit dynamically adjusts an over-current threshold value point ICM; the current value I output by the current sampling and converting unit is used as one input quantity I1 of the over-current threshold value operating unit; the over-current threshold value operating unit dynamically adjusts the input quantity I1 to obtain an output quantity I2 serving as the current threshold value point ICM; the current value I output by the current sampling and converting unit is used as the input quantity ICof the current comparing unit and input into the current comparing unit together with the dynamically adjusted current threshold value point ICM for comparison; and when the current IC reaches the threshold value point ICM, the protection acting unit is triggered for performing protection. Due to the adoption of the technical scheme, the method realizes dynamic adjustment of the current thresholdvalue of a protected object, so that the over-current capacity of a protected object is fully utilized on the premise of not damaging the protected object.