In order to reduce the flow resistance of the thin-film flat plat photobioreactor (FPPBR) and make it more suitable for mass microalgae cultivation, the channel diameter was modified to 0.06 m and the thin-film FPPBR consisted of 10 parallel shunt-wound channels. A thin-film FPPBR system with 100 modified FPPBRs was constructed and used for Chlorella sp. cultivation in desertification areas (Ordos, China) from July to September of 2018. The pressure drop of the modified FPPBR system decreased significantly and the microalgae showed much higher productivity. The pressure drop was about 11.8 kPa when the liquid velocity was 0.238 m s(-1). The final biomass concentration and area productivity reached 2.01 g L-1 and 49.79 g m(-2) day(-1) respectively, and the yearly productivity of Chlorella sp. was estimated to be about 15.24 t ha(-2) year(-1). The results demonstrated that high productivity of Chlorella sp. could be achieved in the improved FPPBR system in desertification areas and the improved FPPBR system was feasible for mass cultivation of microalgae in the commercial application. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.