Abstract: In this paper, to clarify the mining pressure behavior mechanism of the coal face in extra-thick coal seam under the multilayered hard overlying strata, and determine the support resistance reasonably, the multilayered roof breaking law and the support resistance in the extra-thick seam were studied, and the determination principle and calculation method of support resistance were obtained, by using the methods of theoretical analysis, similar simulation and field practice. The results show that the breaking form and breaking order of the multilayered hard roof have obvious influence on the mining pressure behavior, and the support resistances corresponding to single-layer key stratum caving and multi-layer stratum synchronous instability are different It will be difficult to meet the support requirements in extra-thick seam by simply improving the support resistance in the condition of multi-layer stratum synchronous instability. Take one coal face in Datong Mining Area for example, though the reasonable support selection in the extra-thick coal seam and using hydraulic fracturing technology for the hard strata, it has achieved good effect for roof control.

Key words: hard roof, extra-thick coal seam, support resistance, composite cantilever beam, roof breaking form