The invention relates to a starting method and system for a direct current transmission line traveling wave fault distance measuring device. The method includes the following steps that: a post-faultdirect current transmission line voltage condition is acquired according to a direct current transmission line voltage variation quantity; the fault analysis time window of a direct current transmission line is determined according to the post-fault direct current transmission line voltage condition; whether the direct current transmission line malfunctions is judged according to the voltage variation quantity of the direct current transmission line in the fault analysis time window of the direct current transmission line; if the direct current transmission line malfunctions, the traveling wave fault distance measuring device is started. With the starting method and system provided by the technical schemes of the invention adopted, time domain integral transformation is performed on PLC neutral point current signals of a converter station, so that the direct current transmission line voltage variation quantity can be obtained; and the fault component of the voltage variation quantity is extracted; whether the line malfunctions is judged through the fault component; and therefore, the direct current transmission line traveling wave fault distance measuring device can be started reliably to perform wave recording.