Aiming at the resonance problem of cementing control system of offshore platform Modular Drilling Rig(MDR), taking a HZJ450 MDR in the South China Sea as the research object, combined with the classical structural dynamics theory, and according to the characteristics of the MDR vibrating sieve deck support structure, a set of structural dynamics analysis process suitable for practical engineering applications is constructed through the combination of modal analysis, harmonic response analysis, and transient response analysis, and the structural design is improved according to the results of the calculations to meet the requirements of engineering standards. Improve the structural design, reduce the structural velocity and acceleration response, meet the requirements of engineering standards, and reduce the possibility of resonance, the MDR has been completed production application, the effect is good, and further validate the reliability of the analysis method, for the offshore platform MDR structural dynamics analysis to provide an important reference, and can be promoted to the ocean engineering for the large-scale vibration type equipment and structural design.