Abstract: In order to reveal the meso-damage mechanism of physical simulation of coal and rock dynamic disasters, using YYW- Ⅱ uniaxial compression tester and PCIE-8 acoustic emission (AE) monitoring system, the damage space development of samples with different lengths of pre-fabricated single fracture under uniaxial compression are investigated. The results show that with the increase of fracture length from 30 mm to 50 mm, the increasing tensile stress in the prefabricated single fracture area causes tensile damage, and its leading effect on the damage space development of the sample is gradually enhanced, that is, the main damage is produced and concentrated in the central single fracture region, and continuously develop to the top and bottom of the sample. The dominant failure mode of the sample gradually changed from shear failure to longitudinal tensile failure through the middle of prefabricated single fracture.