Abstract: The hydrodynamic characteristics of the flow around the pile-columns directly determine the distribution of the flow force acting on the piles, which is the basis of the flow loads on the inland river frame wharf. Using the computational fluid dynamic (CFD) method, and based on the practical works located at the inland river frame wharf, a two-dimensional numerical simulation model is developed to investigate the hydrodynamic characteristics of the flow around the large diameter four pile-columns arrayed in tandem and parallel or perpendicular to the flow direction. The wake flow field around pile-columns under the conditions of different flow velocities and pile spacings is analyzed systematically. The change law of the flow resistance coefficient, the lift coefficient and the Strouhal number with the flow velocity U and the pile spacing L is revealed. And some studies of the flow field shape and hydrodynamic characteristics of four pile-columns in tandem and parallel arrangement, the influence effects of flow shielding, the influence coefficient of flow shielding and the change of transverse (lateral) influence coefficient at different velocities and the pile spacings are carried out. The results of numerical simulation and analysis can provide some technical references for the calculation of flow loads on the similar pile-columns structures located in the inland river frame wharves.