One destabilizing structure applied in the flat plate photobioreactor was designed, and the flow field and particle trajectory in it were simulated by means of CFD (computational fluid dynamics) to optimize structural parameters of photobioreactor. The results showed that the vertical velocity along the light path was produced in the condition of destabilization, which helps to achieve homogenous mixing of medium needed for microalgae growth. The fluid micelle in the flow field waved regularly, which made the algae cell transmitted between light and dark area and enhance the efficiency of photosynthesis. This destabilizing structure had a great potential to be used in the photobioreactor design. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.