Abstract: A theoretical analyzing approach about a class of seismic isolation systems, RFPS (Rolling Friction Pendulum System), is presented. It starts from the relative kinematics energy theorem in multiply body dynamics. This system consists of two rollers placed in the vicinity of two circular concave curve slides to form the non-indented contacts. Computational results shows that it has the essential capabilities required for an effective isolation system. The rather long vibration period provides the necessary isolation capability, the gravity provides the reposition capability, and the rolling friction acting at the contacting surface on the top and bottom plate respectively, provides the energy dissipation capability. The inter-storey drift resulting from seismic action could be drastically decreased on buildings equipped with a RFPS system. If an optimum combination of slide radius and a rolling friction coefficient is adopted, the seismic isolation effect could be as high as 90%. When the slide radius is in the range of 2m―3m and the rolling friction coefficient less than 0.01, the RFPS system posses good energy dissipation and reposition capability.