A　predictive　decoupling　control　algorithm　using　serial　decoupling　method　is　proposed　to　control　Rotorcraft　UAV(RUAV).　The　dynamic　model　of　the　RUAV　is　decoupled　into　two　sub-systems　with　serial　relation.　Two　model　predictive　control(MPC)　controllers　are　designed　separately　for　the　two　sub-systems,　and　the　serial　relation　is　established　between　them　by　optimal　control　sequence.　The　stability　of　the　proposed　serial　predictive　decoupling　control　algorithm　is　proved.　The　benefit　of　the　proposed　algorithm　is　that　the　calculation　burden　of　the　MPC　controllers　of　decoupled　sub-systems　is　much　less　than　that　of　the　high-dimensional　nonlinear　model　before　decoupling.　Moreover,　the　optimality　of　the　MPC　controllers　of　decoupled　sub-systems　is　greatly　improved　since　the　coupling　effect　is　eliminated.　Experiments　are　done　to　verify　the　effectiveness　and　feasibility　of　the　proposed　algorithm,　and　the　results　show　that　the　proposed　algorithm　is　feasible　and　effective　for　the　flight　control　of　the　RUAV.