The invention provides a distribution network line trip monitoring method which comprises the following steps: 100) sampling real-time loads of a line at a substation master control center every fixed-time interval; 200) carrying out de-noising processing on a real-time load sample set; 300) calculating the basic load; 400) calculating real-time load change rate and real-time load change speed; 500) if the absolute value of the real-time load change rate is smaller than a second threshold value and the absolute value of the real-time load change speed is smaller than a third threshold value, carrying out real-time time update, sampling the real-time loads of the distribution network line and entering the step 400), or otherwise, entering the step 600); and 600) sending warning display information to remind the distribution network line to trip.