A rubber-damped torsional vibration damper (TVD) with two inertia rings arranged in serial way is a new type of damper for reducing torsional vibration of a crankshaft for an engine. Firstly, the construction of a rubber-damped TVD with two inertia rings arranged in serial way (TVD II) is described. If the total moment of inertia(MOI) for the TVD II and other two types of TVD, TVD I and TVD III, are the same and each one with the optimized stiffness, the vibration amplitude for the inertia ring of the equivalent one degree of freedom (DOF) of a crankshaft are calculated and compared. TVD I is a conventional rubber damped TVD with only one inertia ring, and TVD III is a rubber damped TVD with two inertia rings of parallel way. When the MOI or torsional stiffness for the equivalent 1-DOF of a crankshaft is changed, the robustness of torsional vibration reduction are discussed as TVD II, or one of the other two types of TVD is used to reduce torsional vibration of a crankshaft. The method for measurement of the natural frequencies of the TVD II is proposed and an experiment is carried out.