Abstract: By analyzing the inertial forces acting on the engine, this paper deduces the differential equation of vertical vibration, and presents the vibration responses formula with diagrams.In order to properly choose rubber pads to decrease the vibration, the relatonship between the vibration isolation indicator η and the frequency ratio ω/ω_n, with respect to a changing damping ratio ξ is investigated.Finally, the corresponding stiffness parameter k and damping ratio ξ, as well as the type of the vibration isolator, are designed and a rational plan for vibration isolation is established.