The invention provides a method for early warning a wind power plant failure based on polarities of zero mold electric current travelling waves. The method comprises the following steps: collecting the zero mold electric current travelling waves of current collection circuits and all air blower circuits of a wind power plant in real time; comparing the polarities of the zero mold electric current travelling waves of all current collection circuits, selecting one current collection circuit with the distinctive travelling wave polarity; comparing the polarities of the zero mold electric current travelling waves of all air blower circuits of the selected current collection circuit, selecting one air blower circuit with distinctive polarity, and appointing the air blower circuit as a travelling wave disturbing source circuit; calculating the time intervals of three times of latest continuous travelling wave disturbance of the travelling wave disturbing source circuit, comparing the time intervals and the setting time interval, and judging whether the travelling wave disturbing source circuit goes wrong or not. Through the adoption of the technical scheme, failure early warning information inside the wind power plant can be provided in time so as to ensure safe running of the wind power plant.