To investigate the effect of the engine block elastic deformation on the lubrication characteristics of main bearings, a multi-flexible body dynamic model was developed with considering the elastic deformation of the whole engine block and crankshaft. Coupled with the generalized Reynolds equation and Greenwood/Tripp contact model based on the mass conserving boundary condition, the lubrication performances of main bearings were obtained. The results show that when the block elastic deformation is taken into account, the variation trend of the lubrication characteristics are coincident with that without considering the deformation of the engine block; the average of outflow and the total friction power loss show little difference, at the same time, the minimum oil film thickness, the peak oil film pressure and the peak asperity contact pressure have significant variation at certain times of an operating cycle.