Abstract: In order to overcome the disadvantage of conventional single-hole unit water inflow method applied to evaluate on water abundance of aquifer in coal de posits, the observation data of unsteady flow from water drainage test was applied to quantitative evaluation on water abundance of aquifer.An analysis study was cond ucted with the bottleneck effect occurred mechanism and the unsteady flow principle of aquifer and three methods of single-hole unsteady flow method, multiple hole m ethod and group-hole water drainage test method were applied to study hydraulic conductivity under the elimination of bottleneck effect influence and underground wate r with circumfluence and solution algorithm of water storage coefficient for time delay aquifer.The case study results showed that under the different distance observatio n hole, when precipitation rate of water head was 0.46 m/h, the hydraulic conductivity coefficient with a value of 0.20 m2/h would be the unique value.When time delay was 1.52 h, the water storage cofficient would be 1.5x 10-5.The unsteady flow method could be applied to eliminate bottleneck and circumfluence factors. The calculate d parameter results of aquifer were reliable and the selected rational site survey test method approved was prerequisite to accurately evaluate and calculate aquifer par ameters.