This　paper　aims　to　obtain　some　＇universal　method　and　result＇　to　quantitatively　analyze　the　influence　of　contact　resistance　(CR)　on　OTFTs,　which　has　not　been　reported　up　to　now.　This　is　partly　achieved　by　means　of　the　simulated　method　and　the　introduction　of　Rc/Rch0　(the　value　of　CR/on　state　channel　resistance).　To　do　this,　the　OTFT　formula　from　the　Brown　model　is　extended,　and　the　parameter　(errors　carrier　mobility　μ,　saturation　voltage　VDsat,　etc.)　caused　by　Rc　are　analyzed　in　detail.　Then,　the　Rc/Rch0　test　method　is　emphatically　demonstrated,　and　some　meaningful　conclusions　are　drawn.　Based　on　the　conclusion,　it　is　the　first　time　that　a　＇universal　method＇　of　estimating　the　errors　caused　by　Rc　has　been　put　forward.　Experimental　results　further　prove　that　the　method　is　correct.　©　2012　Chinese　Institute　of　Electronics.