The　purpose　of　this　study　was　to　improve　the　critical　current　density　(J　(c))　of　YBa2Cu3O7-delta　(YBCO)　superconducting　films　at　high　magnetic　fields.　Thin　Y1-x　YbxBa2Cu3O7-delta　(Y1-x　Yb　(x)　BCO)　superconducting　films　on　LaAlO3　substrates　were　prepared　by　modified　low-fluorine　metal　organic　deposition　method　(LF-MOD)　in　order　to　investigate　the　effect　of　Yb　substitution　on　the　microstructure　and　superconducting　properties　of　a　YBCO-coated　conductor.　In　this　study,　single-phased,　c-axial-aligned　Y1-x　Yb　(x)　BCO　films　were　obtained.　Yb　doping　had　a　little　effect　on　the　critical　temperature　(T　(c))　and　transition　width　(Delta　T)　values　of　Y1-x　Yb　(x)　BCO　films.　An　abnormal　phenomenon　was　observed　that　the　J　(c)　of　Y1-x　Yb　(x)　BCO　films　at　low　field　was　smaller　than　that　of　the　pure　YBCO　film,　but　the　J　(c)　of　Y1-x　Yb　(x)　BCO　films　at　high　field　was　much　greater　than　that　of　the　undoped　YBCO　film.　Compared　to　pure　YBCO　film,　the　J　(c)　values　of　Y0.75Yb0.25BCO　and　Y0.25Yb0.75BCO　films　were　enhanced　by　a　factor　of　8　at　8　T,　65　K,　which　meant　that　chemical　substitution　of　Yb　into　the　Y　site　could　improve　flux　pinning　significantly　under　the　high　magnetic　field　in　Y1-x　Yb　(x)　BCO　coated　conductors.