In order to design a double-buoy mooring system in the Yalu river estuary for the loading work of 40 000 DWT bulk cargo ships, this paper calculates the wind force, current force, wave force, as well as the total force on the ship based on the practicality of the meteorological condition of this sea area, the data of the vessel, as well as the national criterion, based on which, this paper designs a double-buoy mooring system, determines the size of the mooring buoy, the size and length of the chain, and the size and depth of the deadman. The construction based on this design gains a good effect and thus proves that the calculation and design methods are feasible and effective.