A method is presented for calculating the gravity center of semi-submerged ship based on the hydrostatic data and tank data.The control points of stability changed over ship draft is obtained from stability curve.Then,the construction feasibility of loading the large caisson and special shaped caisson is determined by comparing the height and extreme height of the gravity center of semi-submerged ship,and a database with query function and calculation function is formed,which can be used to provide references for construction.