To　improve　seismic　performance　of　double-deck　frame　bridge　system,　a　novel　precast　double-deck　rocking　frame　bridge　pier　system　is　developed　based　on　ductile　and　rocking　seismic　conception　design　in　this　paper.　In　this　novel　system,　the　upper　columns　are　allowed　to　rock　between　the　precast　cap　beams　to　form　the　rocking　story,　while　the　lower　columns　are　connected　to　precast　cap　beam　and　footings　by　grouted　splice　sleeve　to　form　emulative　cast-in-place　story.　The　seismic　response　of　this　novel　frame　bridge　pier　system　is　investigated.　Nonlinear　equations　of　motion　of　the　system　are　established　following　Lagrange＇s　equation　and　conservation　of　angular　momentum,　and　the　analytical　model　is　used　to　conduct　case　study,　parametric　study　and　stability　analysis.　The　results　show　that　seismic　responses　of　the　lower　columns　of　the　proposed　structural　system　are　smaller　than　cast-in-place　bridge　pier,　while　it　has　an　opposite　trend　for　upper　columns.　The　effect　of　deformability　of　the　lower　story　on　the　stability　of　the　system　is　marginal　for　low-frequency　pulses　or　small　column　size,　while　for　high-frequency　pulses　or　large　column　size　the　deformability　jeopardizes　the　stability　of　the　system.