The invention discloses a fault line identification method based on multi-point monitoring of a distribution network line and a second-order difference of current and voltage phase angle differences.The method comprises the following steps: arranging a plurality of monitoring points on all lines of a distribution network; acquiring a second-order difference of a phase angle difference of currentand voltage signals; acquiring a representative value of each line; and identifying a fault line based on the representative values and locating a fault point. According to the method disclosed by theinvention, a single-phase ground fault line is identified accurately and a zone in which the fault point is located is located accurately.