目的分析某军用柴油机机体的自由模态．方法应用有限元模态分析法对机体进行计算模态分析，并与试验模态法测出的试验值进行对比以保证有限元模型的正确性．结果计算出机体的前五阶非刚体模态，与试验结果相对照比较吻合．结论所建立的有限元模型正确，为下一步的动态响应及动力修正提供了必要的依据． Objective To analyze the free modality of a military diesel engine body. Methods The finite element modal analysis method was used to calculate the modal analysis of the airframe and the experimental data were compared with the test data to ensure the correctness of the finite element model. The results calculated the body’s first five non-rigid mode, in contrast with the test results more consistent. Conclusion The finite element model established is correct, which provides the necessary basis for the next dynamic response and power correction.