An analysis for operating characteristics of piston lubrication system is performed based on the numerical model in this study. Dynamic piston lubrication characteristics such as oil film pressure and thickness distribution can be analyzed through a numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD). In particular, the oil film thickness variation by elastic deformation is considered in the elastohydrodynamic analysis by using the modal reduction method in MFBD system. And this effect is reflected on the fluid governing equations to evaluate the oil film pressure in the lubrication region. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. A numerical example for the piston lubrication system is also demonstrated.