The invention provides a judging method and judging device for the fault direction of a transmission line. The judging method comprises the steps of constructing three current equivalent traveling waves of three current fault transient traveling wave phasors of a transmission line and three voltage equivalent traveling waves of three voltage fault transient traveling wave phasors of the transmission line; integrating the three current equivalent traveling waves and the three voltage equivalent traveling waves to obtain an integral value of the three current equivalent traveling waves and an integral value of the three voltage equivalent traveling waves; comparing the polarity of the integral value of the three current equivalent traveling waves and the polarity of the integral value of the three voltage equivalent traveling waves; and judging the fault direction of the transmission line based on the comparison result. Through the technical scheme of the invention, the reliability of fault judgment of the transmission line can be effectively improved.