The analysis of interaction behavior between fluid and solid is a topic interested to many researchers due to its wide application in engineering. A new discontinuous model coupling the methods of 3D Discontinuous Deformation Analysis (DDA) and 3D Smoothed Particle Hydrodynamics (SPH) is presented for three dimensional analysis of fluid-solid interaction behavior. The motions of solid element (termed block) are analyzed with 3D DDA method while the motions of the fluid element (termed particle) are simulated using 3D SPH method. The contact type between the particles and the blocks is treated as vertex-to-face contact, thus the impact of fluid is applied as point loading on the blocks which is referred to as "penalty-force" method. A method of particle-block contact detection is developed aiming to judge the entrance facet and maintain the interaction with the identical facet during the process of contact interaction to satisfy the criterion that the blocks should be prevent form penetrating by the particles and push them back directly in the case of high velocity impact. A quick sort and search algorithm of particles in the vicinity of the blocks combined with the method of bounding box is introduced for efficient particle-block contact detection. The coupled SPH-DDA provides a promising computational tool to simulate a variety of fluid-solid interaction problems in many potential applications in hydraulic engineering, coastal and offshore engineering, geomechanical engineering, etc.