Abstract: In view of the significant difference between the actual measured value of the roof pressure of the fully-mechanized mining face under the gob of contiguous coal seam and the calculated value by the “transferring rock beam”,the theoretical analysis method is used to determine the roof pressure source of No.21305 fully-mechanized mining face of Daliuta Mine for force source.The method of combining position equation and measured statistics is used to determine the reasonable support working resistance in fully-mechanized mining face under the gob.The result shows that the underground pressure law of fully-mechanized mining face in the gob is affected by a variety of complex factors，showing obvious particularity and difference.The roof pressure on the working face bracket is composed of the direct roof and basic roof rock weights and the additional static load of the gangue from the overlying gob.The gangue above the gob will move in a timely manner in the vicinity of the working face as the support of the working face moves forward,resulting in additional static load effect on it.The theoretical calculation value of “transfer rock beam” has increased significantly; the support average deflection resistance of 12 326 kN and the support average upper resistance of 12 903 kN correspond to excellent roof control effects,and the overrun ratio is small.But when the reasonable support working resistance 12 903 kN is selected ,the overrun ratio is 0 and the support working resistance is relatively high.Therefore,in line with the principle of reducing production costs and reducing investment,the reasonable working resistance of the bracket in No.21305 working face is 12 326 kN.