Abstract: A large-diameter thin-walled steel cylinder is used as the protective structure of a submarine production system. Near the production system, there is a jack-up rig with frequent operations of spudcan penetration. Therefore, the stress and deformation of the steel cylinder during spudcan penetration have attracted many attentions. Centrifuge model tests are carried out to investigate the behaviour of steel cylinders caused by spudcan penetration. Then, CEL method verified by a centrifuge test is used to analyze the influence of spudcan penetration on the stability of steel cylinders under different spudcan-cylinder clearances. The results show that the additional stress and displacement of the cylinder caused by the spudcan penetration decrease with the increase of the spudcan-cylinder clearance. And the reduction degree decreases with the increase of the spudcan-cylinder clearance. Due to the different spudcan-cylinder clearances, there are two stress modes for the steel cylinder. When the clearance is twice the diameter of the spudcan, the additional stress of cylinder can reach 110 MPa, indicating that the affected distance of the spudcan penetration on cylinder can reach more than 2 times the spudcan diameter.