For deep foundation pit near a river, groundwater control is the key problem of foundation pit design. Based on a deep foundation pit in watery sand-gravel ground near a river, the dewatering scheme is discussed by using JGJ 120-2012, GB50296-2014 technical specification and theoretical formula near a river. The numerical method of groundwater seepage is also used to assist the optimal design of the dewatering scheme. According to the calculation results of JGJ 120-2012 and GB50296-2014 technical specification, the distance of tube well is 20m. However, it was found that water accumulated in the foundation pit near the river in the engineering practice. Combined with the theoretical formula of foundation pit along river and the numerical simulation results, the reasonably well spacing should be between 9m-10m. According to research result, the problem of water accumulation in the foundation pit was solved by adding 13 tube wells.