Movement of the grab excavation process and stress state is the key to conduct large grab design. In this paper, discrete element theory is used to the simulation study of the large marine dredging digging grab process. Through the simulation of large-scale grab EDEM without deep reclaiming process, we get all the key parts of the grab variation of the force. Provide reference to reasonably determine speed of, hopper shape, arc discharge baffle structure, in order to design Grab mechanism design and improve the efficiency and reduce energy consumption.