The invention discloses a power flow control method for a flexible direct current power grid. If an asymmetrical running line is in direct current lines connected with a converter station, the current of positive and negative lines, which are in a symmetrical running state, of the direct current lines is controlled to be symmetrical. According to the power flow control method for the flexible direct current power grid, if asymmetrical line running is caused by unipolar disconnection faults in the direct current power grid, the power flow of other positive and negative lines is purposefully controlled; other lines are prevented from overloading; the running performance of the direct current power grid is effectively improved; the grounding current of the converter station without disconnection faults is small; and the method has a good application prospect.