An　experimental　investigation　on　the　flow　characteristics　of　falling　liquid　film　outside　horizontal　tubes　under　conditions　of　no　heat　exchange　have　been　performed　in　the　present　study.　A　bi-polar　type　conductivity　probe　was　constructed　based　on　the　conductance　theory,　and　was　used　to　measure　the　film　thickness　distributions　of　the　falling　film　around　horizontal　tubes　under　different　conditions.　The　test　section　was　made　up　of　copper　tube　with　a　diameter　of　25.4　mm,　and　a　length　of　300　mm.　The　experimental　conditions　were　as　follows:　the　flow　rate　Q　=　50~250　L　·　H-1and　the　vertical　gap　between　horizontal　tubes　h=25,32,40　mm,　respectively.　Effects　of　the　film　flow　rate,　the　vertical　gap　between　tubes,　the　circumferential　positions　and　the　axial　positions　on　the　falling　film　thickness　distribution　around　horizontal　tubes　were　verified,　and　some　conclusions　were　reached.