The　internet　of　things　(IoT)　attracts　great　interest　in　many　application　domains　concerned　with　monitoring　and　control　of　physical　phenomena.　However,　application　development　is　still　one　of　the　main　hurdles　to　a　wide　adoption　of　IoT　technology.　Application　development　is　done　at　a　low　level,　very　close　to　the　operating　system　and　requires　programmers　to　focus　on　low-level　system　issues.　The　underlying　APIs　can　be　very　complicated　and　the　amount　of　data　collected　can　be　huge.　This　can　be　very　hard　to　deal　with　as　a　developer.　In　this　paper,　we　present　a　runtime　model　based　approach　to　IoT　application　development.　First,　the　manageability　of　sensor　devices　is　abstracted　as　runtime　models　that　are　automatically　connected　with　the　corresponding　systems.　Second,　a　customized　model　is　constructed　according　to　a　personalized　application　scenario　and　the　synchronization　between　the　customized　model　and　sensor　device　runtime　models　is　ensured　through　model　transformation.　Thus,　all　the　application　logic　can　be　carried　out　by　executing　programs　on　the　customized　model.　An　experiment　on　a　real-world　application　scenario　demonstrates　the　feasibility,　effectiveness,　and　benefits　of　the　new　approach　to　IoT　application　development.