The analysis of single-phase grounded fault in a distribution power system shows that the overall trends of the initial stage in zero-sequence current between the fault feeder and the sound feeder are opposite.Thus，a novel fault line selection approach employing the Hough transform to detect the overall trends of the initial stage in zero-sequence current is proposed.The data of zero-sequence current after fault is transformed by utilizing the Hough transform，and then constructing an overall mutation direction angle of the overall trends of the initial stage in zero-sequence.The initial direction trend polarity of zero-sequence current of faulty line is different from the whole mutation polarity，while in non-fault line it is the same as the whole polarity of power frequency variation.The Hough transform based method is simple in theory and significantly relaxes the requirement of sampling rates.Substantial simulation results illustrate the method is accurate and reliable.