The invention discloses a long wall coal mining roof pressure hydraulic support resistance change characteristic pre-warning method. A hydraulic support working resistance monitoring device, a pump station switch monitoring device and a hydraulic support resistance change index dynamic monitoring system are used for pre-warning; the hydraulic support working resistance monitoring device is used for recording and storing monitored working face hydraulic support working resistance and corresponding time in real time; the pump station switch monitoring device is used for recording and storing monitored working face hydraulic support injection pump pressure finishing time; the hydraulic support resistance change index dynamic monitoring system is used for processing and analyzing received data, marking a hydraulic support working resistance value corresponding to the working face hydraulic support injection pump pressure finishing time as hydraulic support setting load, and pre-warning about working face roof pressure according to the change of resistance change index values. Accurate and timely pre-warning about abnormal roof pressure can be realized, and normal periodic weighting length can be accurately determined in real time.