The invention discloses a flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering. According to the invention, during the inner loop controlling process of a flexible direct-current current, the nonlinear filtering is carried out for a voltage feedforward link. The method specifically comprises the following steps: extracting each sequence component of an alternating-current voltage amplitude; calculating the N sampling point average values of the sequence components; comparing a current average value with the output result of a nonlinear filter in a previous period; and correcting the output result of the nonlinear filter in a current period. The output result is a fixed value which changes in a gradient mode and acts on the voltage feedforward link of the inner loop. The beneficial effects of the invention are as follows: the high-frequency resonance of a flexible direct-current and alternating-current system caused by impedance matching can be effectively inhibited. Meanwhile, the rapidity is achieved and the adjustment can be carried out along with alternating voltage when voltage disturbance such as alternating current faults occurs. The over-current risk of the converter valve is reduced. The method only needs to be achieved in the flexible direct-current secondary control software link, wherein no primary device needs to be additionally arranged. The method is low in cost, free of land occupation and convenient for engineering practice.