The inertial concretionary coarse alignment of strapdown inertial navigation system（SINS）is proposed for the condition that the vessel moor along the dock or on the sea.The gravity vector is integrated on the inertial frame and inertial concretionary frame respectively.And the method utilizes the direction variation of gravity vector for the earth rotation.The strapdown attitude matrix is estimated.The advantage of the proposed method is the disturbed accelerate aroused by liner displacement that are wiped off and rotation velocity by sway are avoided effectively.The simulation and analysis show that the proposed inertial concreted coarse alignment is superior to the conventional one.