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.