Abstract: A non-grid hydrodynamic numerical model is established by using the moving particle semi-implicit (MPS) method to investigating the possibility of the model in the research of the hydrodynamics of the coastal structures under the action of water movement.Without grids,the interaction effect among neighboring particles can be simulated by means of the kernel function,based on which the governing equation is discretized by establishing the smoothing model,the gradient model and the second-derivative model (i.e.the Laplacian model).The incompressibility of the fluid is determined by introduction of a socalled particle density number.The model is free from limitation through complex shape of rigid boundary and arbitrary defomation of the free surface,and thus has the adaptability to special practical situation.In the end,collapsing process of a water column impinging an upright wall after by-passing a set of perforated blocks is simulated by using the MPS model.The numerical results show that the peak value of the pressure in the case of the perforated blocks decrease by 42% compared with the case without perforated blocks.