The light spectrum is an important parameter that affects microalgae growth, but to date has not been thoroughly studied in microalgae biofilm-based systems. In this study, the effect of light spectra on biofilms of two microalgae (Chlorella sp. and Nannochloris oculata) was explored by investigating their growth, photosynthetic property, and main organic composition cultured under white, blue, green, and red light. The results indicated that blue light and red light were more efficient in enhancing cells' growth than white light. Microalgae cultured under blue light had higher photosynthetic and photoprotective capability. The highest lipid accumulation was achieved for microalgae cultured under blue light, while the highest carbohydrate accumulation was obtained under red light. Protein accumulation in cells cultured under these four light conditions were almost the same. The results of this study may have important implications in selecting suitable light spectra for microalgae biofilm-based cultivation systems. (C) 2020 Elsevier Ltd. All rights reserved.