In　this　paper,　we　presented　the　result　of　YBCO　films　deposited　epitaxially　on　both　SrTiO3　single　crystal　and　textured　Ag　substrates　by　a　TFA-MOD　method.　The　growing　conditions　and　forming　mechanisms　of　the　YBCO　films　on　these　two　kinds　of　substrates　was　investigated　systematically.　It　was　found　that　the　precursor　film　coated　on　Ag　substrate　took　less　time　to　completely　decompose　to　an　amorphous　precursor　film　during　the　first　stage　of　the　calcination　than　that　on　SrTiO3　substrate.　Moreover,　the　higher　temperature　was　needed　to　obtain　pure　YBCO　phase　on　Ag　substrate　during　the　second　annealing　stage.　A　possible　growing　mechanism　for　this　difference　was　described.　A　transport　j,　value　of　1.5　x　10(4)　A/cm(2)　(at　77　K)　was　obtained　for　the　YBCO　film　deposited　on　Ag　substrate,　while　the　film　on　SrTiO3　substrate　exhibited　an　a　T-c　onset　of　92　K　and　a　high　jc　value　of　2.3　MA/cm(2)　at　77　K　in　self-field　was　measured.