The cultivation of microalgae in biofilm has been a potential way to overcome the shortcoming of conventional algal culture modes of open pond and photobioreactors in liquid suspension. However, the growth characteristics and related effect factors of the biofilm are still far from being understood. In this work, oleaginous microalgae species Pseudochlorococcum was cultured in an attached biofilm and influential factors on the growth rate of biofilm were investigated. The results showed that Pseudochlorococcum sp. preferred to accumulate more biomass on hydrophilic substrata than on hydrophobic one. The photon flux density of 100 mu mol m(-2) s(-1) was its light saturation point. The optimal inoculum density was about 3-5 g m(-2). The appropriate concentrations of nitrogen, phosphorus in medium and CO2 in aerated gas were determined as 8.8, 0.22 mmol L-1 and 1 %, respectively.