Studying　biofilms　in　long-distance　raw　water　diversion　pipe　is　beneficial　to　the　analysis　of　water　quality　and　the　security　of　raw　water　quality.　Therefore,　the　characters　of　morphology,　microstructure,　spatial　and　temporal　distribution　of　biomass　and　microbiota　community　of　bio-films　in　long-distance　raw　water　diversion　pipes　were　investigated　using　the　simulated　process　of　8　bio-film　annulus　reactors　(BAR)　in　series　with　different　raw　water.　The　results　showed　that　the　bio-film　structure　was　significant　different　in　water　quality,　and　the　particle　color　attached　in　pipe　bio-film　was　an　important　influencing　factor　in　the　characters　of　morphology.　Secondly,　the　structure　of　the　rough　bio-film　changing　with　water　flow　increased　the　specific　surface　area　of　the　bio-film　which　led　to　the　growth　and　development　of　bio-film　and　pollutant　removal.　Thirdly,　the　biomass　of　A　raw　water　reached　the　peak(1.11　nmol·cm-2)　in　BAR3　running　75　d,　and　then　became　lower　due　to　the　less　nutrient.　However,　the　biomass　along　simulated　pipes　of　B　water　changed　subtly　because　of　the　limited　DO(0.3-3.0　mg·L-1).　Finally,　the　microbiota　composition　is　highly　correlated　with　the　water　quality,　reacting　water　quality　and　purification　effect.