The invention provides a harmonic unidirectional transfer characteristic analysis method for an MMC converter station, which belongs to the technical field of converters. The harmonic unidirectional transfer characteristic analysis method for the MMC converter station provides technical support for the research on the degree of disturbing of a flexible direct current system fault on the stable operation of an alternating current system in a next step. The method provided by the invention comprises the steps that a control system simulation model of the MMC converter station is set up; the set model is simulated, and the amount to be researched is detected; a correlation index is used to analyze positive and negative bus current of the direct current side; from the perspective of energy leakage, the magnitude of harmonic energy transferred from the direct current side to the alternating current side is analyzed; the slope between two adjacent points is acquired; an approximate extreme point and a inflection point are found; and a least squares method is used to acquire the segmentation fitted curve of a harmonic energy transfer efficiency function. The method provided by the invention can quickly determine the leakage severity of any harmonic energy from the direct current side to the alternating current side in a specified frequency range.