In this paper, the oil pan of engine is taken an example to study, analyses the dynamic characteristics by the method of hybrid modeling, gaining the modal frequency and vibration mode of the oil pan. According to the results, measures to improve the structure of the oil pan are put forward, and the modal analysis and acoustic test have been made. The results show that, by increasing the stiffness of the oil pan that makes modal frequency density decreases, it reduces the possibility of resonance occurring, oil pan radiation noise contribution rate decreased to engine noise.