Abstract: In order to quantify the damage and failure process of soft coal body, for the coal body in Huainan mining area, using briquette instead of raw coal, the monitoring test of acoustic emission characteristics of coal body under compression is carried out, and the damage variable D is defined by cumulative AE counts. The damage evolution characteristics of coal body are studied. With the increase of axial strain, the damage variable of coal body shows a trend of stable, slow growth, rapid growth and then stable. The expression of coal constitutive relationship is deduced, and the rationality of the theoretical constitutive model is verified. The total stress-strain curve obtained by the theoretical constitutive model is consistent with the test results. The average absolute error between the theoretical stress value and the test value is only 0.126mpa, which realizes the theoretical description of the stress-strain relationship of soft coal. The research results can provide experimental and theoretical basis for revealing the mechanical response characteristics of failure and instability of soft coal and preventing and controlling instability disasters.