Aim\ The finite element model of the combined structure of block of a heavy duty diesel with crankshaft is established for modal analysis. Methods\ The dynamic substructuring method is applied to establish the finite element model

and virtual material is applied to simulate the dynamic characteristics of interface between the complex combined structure. Results\ The first five natural frequencies and the modal shape calculated with this modelis very close to the experimental result. Conclusion\ The finite element model is correct

and a basis for the dynamic simulation study for the engine is provided.