Abstract: A direct numerical simulation method was developed for solid-solid collision in fluid. The sharp interface immersed boundary method was used to simulate the dynamic boundary problems in fluids, which avoids the negative volume error in the body-conforming mesh method. The finite element method based on the penalty function was used to simulate the motion and collision of the solids. The coupling solution of the fluid domain and the solid domain was realized in the partitioned coupling approach. Comparison of the experimental data of normal collision and oblique collision between spherical particles and the wall verifies the validity of the numerical simulation method. The variation of the flow field before and after the collision was obtained. The contact force and stress in the solid domain were also got with the numerical simulation method. This model is applicable to fluid-flow environments such as the abrasion of solid particles on pipes, the fluid-induced collision between ocean risers, the impact of falling objects on submarine pipelines and so on.