To improve biofilm activity and obtain a high hydrogen production performance of biofilm photobioreactor (BPBR), the biofilm growth on the fiber-optic surface was optimized by using a multi-sensor measurement system, plus biofilm thickness automatic control device. The proposed measurement system consisted of three types of sensors, i.e. biofilm thickness sensors, biomass concentration sensor and fiber Bragg grating temperature sensors, respectively, to monitor biofilm growth and distribution, cell adsorption/detachment rates, cell metabolic heat production and distribution in time-dependent tests. The biofilm thickness was controlled in real time using the designed biofilm control device and the information obtained from the biofilm sensors. The biofilm, in the improved BPBR, showed a loose structure and high hydrogen production activity. The H-2 concentration and H-2 production rate reached a high level of 45 mu g/mL and 2.72 mmol/L/h, respectively, for the improved BPBR; these values were 1.73 times and 1.49 times those of the unimproved BPBR, respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.