Abstract: In order to investigate the phenomenon of scale effect in the bursting failure of coal measure,the bursting failure tests under uniaxial compression conditions were carried out on square coal samples with different sizes by using the house-developed test apparatus. The acoustic emission characteristics during the bursting failure of the coal samples were investigated. The study shows that as the sample size increases,the elastic modulus of coal increases and the compressive strength and peak strain decrease. For larger samples,ejections of small fragments from the skin of the sample trend to occur before the final catastrophic bursting failure. This phenomenon is unlikely to occur for small samples. As the sample size increases,the growth rate of acoustic emission events increases,and the number of AE events with large energy increases. This size effect trends to disappear when the sample size reaches 300 mm. The acoustic emission b-value of large size specimen produces sudden drop due to localized bursting failure. The distribution characteristics of the acoustic emission events reflects the damage mode of coal sample. The distribution of acoustic emission events trends to become more dispersed as the coal sample becomes larger,and the damage mode of specimen is changed from shear damage to tensile damage.