An Ocean Casing Pipes Centering Equipment is designed and implemented. Utilizing the equipment, two casing pipes can be fastened together by means of welding. The equipment can automatically carry out clamping and centering two casing pipes, and then the butt welding is conducted at their adjacent ends. In the development of this equipment, some advanced means, such as digital modelling and FEA (Finite Element Analysis), are taken full advantage of. First, all the parts’ 3D models are built with Pro/Engineer. Then, those digital parts is assembled in Pro/E assembly environments. Meanwhile, assembly interference detection is executed. Furthermore, by means of universal finite-element software，the finite element model is constructed. The strength and stiffness of the structure is calculated and analyzed so that the faults of the equipment can be found out in design stage. Through repeating this designing and verifying course, the structure of the equipment can be improved.