In this paper, we propose a structural linear dynamic analyses simulation method using the reduced order modeling to efficiently evaluate frequency response and transient analyses in the field of ocean engineering. The commonly used mode superposition method cannot guarantee the accuracy of analysis results for local loads. Accordingly, the reduced order model is constructed using the algebraic dynamic condensation method that considers the automatic substructuring of large-scale structures and the inertial effect. The performance of the proposed method is verified using several structures used in several ocean engineering fields.