Abstract: In view of the disadvantages of the current coastal erosion protection: high construction and maintenance cost, difficult construction, long construction period, high self-weight and limited scope of protection, the use of geogrid cage is proposed, with advantages of inexpensive ness, easy construction, low self-weight, high corrosion resistance and low maintenance cost. The shape of the grating cage will influence the effect of coastal erosion stability. Based on the numerical analysis method of explicit dynamics, for the three shapes of grating cages with square section, circular section and wave-shaped section, the wave load is simulated by piston wave making and the hydrodynamic method of SPH smooth particles is used to simulate the water body. The contact between the water body and the geogrid cage and that between the water body and the soil body are simulated by using the global property-assigned generic contact, and the tangential contact force between the geogrid cage and the coastal soil body is determined by using the penalty function. The force and displacement of geogrid cage and coastal soil body under wave load with and without geogrid cage and three shapes are analyzed with wave time history and peak value characteristics. The area with the greatest overall force of the geogrid cage is near the sea level. The use of the geogrid cage can reduce the influence of the wave on the bottom eddy current in the vertical cliff surface, and the wavy geogrid cage has a remarkable effect on the protection of coastal erosion.