In the wharf dredging project, the mud discharge pipe will drift on the water pipeline and collide with the pile foundation under the wharf due to the drag force of the water flow, which will adversely affect the safety of the equipment and the construction efficiency. In order to solve the above problems, this paper uses numerical simulation method to establish a calculation model of the drag force of the mud discharge pipe, and uses the engineering-scale prototype indoor floating pipe towing test and the Morison theory calculation method to verify it. The drag force of a single sludge discharge pipe under different flow rates and conveying concentrations was analyzed, and the research results were applied to the pipeline force analysis of typical wharf dredging projects. The results show that the results of Morison's theoretical calculation are similar to those of numerical calculation at low flow velocity, and conservative at high flow rate, with a difference of about 10%. When the flow velocity is less than 0.8 m/s, the drag force increases slowly with the flow velocity. When the flow velocity is greater than 0.8 m/s, the drag force is approximately linearly correlated with the flow velocity and increases rapidly. The submersion depth of the floating pipe under different conveying concentrations was determined, and the drag force was approximately linearly positively correlated with the submerged depth. Under the four flow velocities of 0.6–1.2 m/s, the submerged depth of the floating pipe increased from 0.4 m to 0.7 m, and the drag force increased by 453.9 N, 806.4 N, 1260 N, and 1814.4 N, respectively. For a wharf dredging project, the above method is used to calculate the drag force of the water flow to be 27000 N, and two pipeline anchoring improvement schemes are proposed to provide scientific guidance for the laying of water sludge discharge pipes in the wharf dredging project.