Condensing　heat　transfer　of　R134a　on　horizontal　single　plain　and　integral-fin　tubes　was　investigated　by　both　computational　and　experimental　methods.　The　VOF　model　and　Lee　condensation　model　were　utilized　in　the　simulation.　Validation　of　the　model　was　performed　with　two　different　refrigerants.　Condensing　heat　transfer　coefficient　for　plain　and　integral-fin　tubes　were　calculated　in　comparison　with　the　experimental　data　and　Nusselt　analytical　solution.　Instantaneous　film　flow　characteristics　of　condensation　on　horizontal　single　plain　and　integral-fin　tubes　were　discussed　respectively.　Contours　of　liquid　volume　fraction　for　the　plain　tube　and　condensing　heat　transfer　coefficient　for　the　plain　tube　at　different　time　with　T-w　=　303　K　are　presented.　For　integralfin　tubes,　contours　show　that　the　thickness　of　liquid　film　at　lateral　fin　surface　is　much　smaller　than　that　at　root　fin　surface.　Comparison　between　R134a　and　R11　were　made　and　it　was　found　that　different　surface　tension　could　lead　to　different　liquid　film　distribution　which　could　result　in　different　heat　transfer　performance.　Experiments　involving　the　same　fin　structure　were　also　conducted　to　verify　the　theoretical　model　and　a　satisfactory　agreement　between　simulation　and　experimental　results　was　found.