At present， prefabricated structure and industrial construction are the key development directions in civil engineering. Precast upper cylinder and lower foundation structure with embedded cup type connection， as a typical prefabricated structure in the field of offshore civil engineering， has fundamental research value. Based on rigid theory， finite element method（FEM） and elastic theory， the mechanical characteristics of this type of connection structure are studied， and relevant theoretical calculation formulas are derived. It is found that if the grouting bond is reliable and the connection between the cup and the upper cylinder is fixed， the structural deformation is small. If the grouting bond fails， there will be friction slip between the cup and the upper cylinder， resulting in a large displacement， and the displacement of the upper cylinder decreases with the increase of

h

c

（height of the cup）. When hc is not less than 3.0 m， the displacement value is relatively reasonable. Compared with the calculation formula by rigidity theory， the simplified elastic formula based on deformation pattern of the upper cylinder and the theory of contact friction gives close result to that of FEM， and the details are as follows： when the cup height is 2.0 m， the average error is about 10%； when the cup height is 3.0 m and 4.0 m， the average error reduces to about 7% and 6%. The results show that the simplified elastic formula is feasible.