Abstract: In view of the excessive dewatering of roof water caused by qualitative analysis, the attenuation rate of water inflow in borehole, the head height of aquifer, the total amount of water dewatering and the residual water are chosen to quantitatively evaluating dewatering of Dananhu Coal Mine 1305 working face in Xinjiang Province, especially in the core of fold.The results show that the total amount of water dewatering is less than static reserve, the attenuation rate of water inflow in borehole in synclinal shaft is small, and the head height of aquifer is 45 m higher than the roof of aquifer. All of this indicates that the dewatering effectively is unrealized, which should be appending drill holes to dewatering. It can provide a certain quantitative basis for quantitative evaluation on dewatering of roof water and make sure the dewatering effectively.