The surface of submerged macrophytes is often enriched with organic matter, sand, bacterial micelles, algae and microorganisms to form the epiphytic biofilms, which play a significant role in the process of lake biogeochemical cycle. Three different leaf shaped submerged macrophytes were selected in Lake Caohai:Ceratophyllum demersum, Potamogeton maackianus, and Potamogeton lucens L. The morphology, physicochemical characteristics and algae in the epiphytic biofilms of the different submerged macrophytes were studied. It has studied the accumulation characteristics of heavy metals Cd and Pb in the epiphytic biofilms. The results showed that 6 phylums, 8 classes, 17 orders, 29 families, 65 genuses and 81 species of the epiphytic biofilms of the three submerged macrophytes were identified, mainly belong to Cyanobacteria, Chlorophyta and Bacillariophyta. The algae functional groups of different epiphytic biofilms have different compositions; Redundancy analysis shows the water environmental factor can explain 88.3% of the changes of algae functional group; The changes of iron (Fe), manganese (Mn), total nitrogen (TN) and total phosphorus (TP) contents in different epiphytic biofilms of submerged macrophytes are:Ceratophyllum demersum > Potamogeton maackianus > Potamogeton lucens L.; The accumulation of heavy metals in the epiphytic biofilm of submerged macrophytes is selective. The accumulation of Pb is large (11.41-41.31 mg/kg), and the accumulation of Cd is low (0.59-5.76 mg/kg). The accumulation of Cd in epiphytic biofilm is equivalent to that of macrophytes (0.44-5.56 mg/kg). The accumulation of Pb in the epiphytic biofilm is significantly correlated with the Cryptophyta and diatom biomass among epiphytic algae biomass and the contents of Fe, Mn and TN in the epiphytic biofilm. However, there was no correlation between Cd accumulation and various indicators in biofilm. The role of epiphytic biofilm of the submerged macrophytes in the process of pollutant transformation need to pay more attention in the grass-type lakes.