In response to the problem of more influence factors and difficulties in identifying the depth of damage floor of coal seam

six factors including mining depth

mining height

incline section length (working face)

dip angle

floor lithological combination and roof lithological combination were selected to research the depth of damage floor by analyzing two aspects influential elements of the deformation degree of the floor rock

geological model was generalized and six factors and five levels orthogonal numerical simulation experiment were carried out with mine 4602 working face as the background. The experimental results showed that: (1) The main factors influencing the depth of damage floor were incline section length

floor lithological combination

roof lithological combination

mining depth and mining height were weakened in order

dip angle was weakest; (2) that roof lithological combination was the key factors in influencing the floor damage depth was made clear for the first time; (3) prediction model of mining depth of damage floor on incline section length - floor and roof lithological combination - mining depth - mining height - dip angle was established

the calculation results were more close to reality comparing with the results of mining regulation empirical formula calculation

and the precision was high

the error was low

and it can meet the engineering use basically. The results of the study had a positive guiding significance on the research of the depth of damage floor and engineering application.