Abstract: In order to monitor the state of cemented backfill in coal mine, based on the characteristics of continuous mining and continuous filling technology and the characteristics of backfill, five basic contents of backfill state monitoring are proposed, mainly including liquid level monitoring, stress monitoring, strength monitoring, temperature monitoring and stress monitoring. The monitoring technology and monitoring scheme of each monitoring content are studied. The liquid level monitoring technologies such as reserved borehole, laser, radar and buoy are analyzed. It is considered that the buoy type liquid level monitoring has good adaptability; The retaining wall manometer is used for stress monitoring, with a range of about 150kPa; The monitoring technology of filling body tested in laboratory is put forward, and the in-situ strength testing technology is prospected; Temperature monitoring is realized by temperature sensor; KPa and MPa dual channel stress gauges are used for stress monitoring.