Rigid　Frame　Bridge　was　widely　used　while　the　according　seismic　design　was　quite　difficult　and　worth　of　discussion.　Section　sizes　of　piers　were　increased　when　elasticity　seismic　theory　was　adopted;　plastic　hinges　were　designed　on　the　top　or　bottom　of　piers　when　ductility　seismic　theory　was　employed;　and　isolation　bearings　were　installed　when　seismic　isolation　theory　was　applied.　However,　larger　size　may　neither　be　cost-effective　nor　meet　the　requirements　of　seismic　design.　Furthermore,　seismic　rehabilitation　would　be　extremely　difficult　when　plastic　hinges　were　employed,　and　isolation　bearings　were　not　applicable　to　Rigid　Frame　Bridge　as　there　was　nowhere　to　place　them.　A　new　method　was　proposed　for　Rigid　Frame　Bridge　referred　as　base-isolation　design.　Based　on　introducing　base-isolation　concept,　base-isolation　design　of　Rigid　Frame　Bridge　was　achieved　by　setting　seismic-isolation　layer　in　cap.　There　were　four　kinds　of　base-isolation　systems　widely　adopted　in　numerical　investigation　of　base-isolation　for　Rigid　Frame　Bridge,　i.e.,　laminated　elastomeric　bearings　(EB)　system,　lead　rubber　bearings　(LRB)　system,　EB　and　liquid　viscous　dampers　(EB-LVD)　system,　and　LRB-LVD　system.　It　was　found　that:　i)　seismic　effect　transmitted　to　superstructure　and　substructure　of　bridge　could　be　dramatically　reduced　by　seismic-isolation　layer;　ii)　efficiency　of　base-isolation　system　could　be　significantly　promoted　by　using　EB　and　LVD　together;　iii)　mechanical　parameters　of　isolation　devices　should　be　determined　according　to　the　actual　situation　of　the　bridge.