Abstract: This paper presents an optimization of multi-well dewatering for the Quaternary bottom aquifer above the panel 6311 in a coal mine based on optimal objective function. The minimum drainage is selected as the target function and groundwater levels at the controlling points as the primary constraint conditions. The calculated safety water head for preventing quicksand is selected as the water level of controlling points, and the optimal objective function is then used to optimize the design. The result indicates that the optimized drainage is reduced by 20% compared with the result calculated with the model of a fully penetrating well in a confined-unconfined aquifer, meeting the same requirement for groundwater levels. The result reveals the pump-output of every dewatering well, that will be helpful for choosing the position and equipment of the dewatering wells.