Abstract: Low-strength cemented tailings backfill （CTB） may be in the post-peak failure stage when controls ground pressure in backfill mining.The post-peak stress-strain curve characteristics and the acoustic emission（AE） parameters of CTB are closely related to the control of ground pressure.Therefore，uniaxial compression experiments and AE tests of CTB from unclassified tailings of Chengchao Iron Mine with cement-tailing ratio of 1:6 are conducted to obtain the stress-strain curve and the AE parameters.The post-peak stress-strain curve characteristics and failure process of CTB are analyzed based on AE energy rate and AE event.The result shows that the slope value of the post-peak stress-strain curve of CTB is negative，which decreases firstly，then increases and keeps a constant finally.The post-peak stress-strain curve could be divided into stage AB，stage BC and stage after C according to its slope variation.During stage AB，the stress-strain curve gradually becomes steeper and its slope value decreases with a convex sharp.The macroscopic cracks on the surface of the filling body increase gradually and the strength deterioration accelerates.The energy rate decreases dramatically，then increases rapidly and AE event location point concentrate partly.When the CTB enters the BC stage，the stress-strain curve becomes slow and its slope increase with a concave sharp.The macroscopic shear plain appears because of the expansion and convergence of shear cracks and the failure process becomes slower. The energy rate is high and decreases with AE event location points gathering into a strip.At the stage after C，the slope of the stress-strain curve keeps a constant.The shear plain slips and external load is supported by residual structure of CTB.Meanwhile，the energy rate and AE event reduce significantly.The post-peak AE parameters of CTB can well reflect its characteristics of stress-strain curve and the failure process.

Key words: Filling mining, Filling body, Uniaxial compression, Characteristics of stress-strain curve, Acoustic emission parameters