For a large offshore substation located in Rudong, China,a multiple-scale finite element model of the lifting trunnion of the jacket is built by SACS software. A series of numerical analyses are conducted to investigate its strength behavior under different trunnion types and the use of stiffened plates. A local finite element model of the lifting trunnion is also built by ANSYS for comparison. The difference in the calculation results between the multiple-scale finite element model and the local finite element model is explored. The results show that the setting of diagonal braces is of little effect on the strength of the trunnion, but the stress concentration is obviously improved by stiffened plates. In addition, the results of the local finite element method are relatively more conservative.