This paper presents the influence of radiated noise from engine surface depending on assembly condition between engine block and oil pan. At the first, force at the crank bearing is obtained from multi-body dynamics model. Secondly, modal analysis is operated to define mode contribution and modal participation factors at the Structure – FEM model for virtual cylinder block. Thirdly, the radiated noise is calculated by Acoustic-FEM. Above procedure is applied at rigid connection model and sandwich panel connection model. Connection properties are applied between engine block and oil pan. Finally, the sound quality of the radiated noise at each condition are compared.