In order to recognize traveling-wave head in railway power transmission line, this paper puts forward a new algorithm. Based on the existing discrete signal processing, singularity detection of traveling-wave signals is realized through the derivation method in the difference form. Through combination of the modulus maxima method with the threshold constraint decision function, the weak adaptability of the discrete derivation is overcome and the fault point location is identified accurately. The algorithm has simple principle and small amount of calculation. Recorded on-site data show that the proposed algorithm is correct and effective, and it possesses high reliability with absolute distance-measuring error of no more than 100 m.