In　order　to　study　the　characteristics　of　composite　microbial　fouling　and　the　method　of　restraining　fouling　in　the　future,we　chose　iron　bacteria　(IB)and　slime-forming　bacteria(SFB)as　the　research　objects　which　are　the　most　common　in　microbial　fouling.　An　experimental　study　was　carried　out　on　the　plate　heat　exchanger　for　the　relationship　of　the　two　bacteria　in　the　composite　microbial　fouling　formation　and　the　fouling　characteristics　under　different　conditions.　The　results　show　that　the　microbial　fouling　has　obvious　induction　period.　The　asymptotic　value　of　fouling　resistance　of　the　iron　bacteria　is　2×10-4m2·K/W,and　the　asymptotic　value　of　fouling　resistance　of　the　slime-forming　bacteria　is　1.2×10-4　m2·K/W.　The　iron　bacteria　have　strong　ability　of　fouling　formation　than　the　slime-forming　bacteria.　The　fouling　resistance　of　mixed　bacteria　with　the　proportion　1:1　is　between　the　two　above.　No　matter　what　kind　of　bacteria　occupy　the　main　volume,synergistic　effects　between　the　two　kinds　of　bacteria　prompt　the　ability　of　the　fouling　formation.　The　asymptotic　values　of　fouling　resistance　of　the　mixed　bacteria　in　30　is　lower　than　it　in　35,and　the　time　get　to　stabilization　is　twice　that　of　35.　The　velocity　has　obvious　effect　on　the　composite　microbial　fouling　characteristics.　The　asymptotic　values　of　fouling　resistance　of　the　mixed　bacteria　in　0.1m/s　is　twice　that　of　0.15m/s,and　the　time　get　to　stabilization　is　2.7　times　that　of　0.15m/s.　©　2016,　Chemical　Industry　Press.　All　right　reserved.