Abstract：Air gap membrane distillation system is an efficient distillation technology .Characteristics of membrane surface flow field is very important for improving the heat transfer and mass transfer efficiency of the air gap membrane distillation system. The transient flow field and turbulence field at the membrane surface were studied with high frequency PIV system in this paper. The transient flow field showed the vortex from the generation to disappear. Turbulence intensity of the flow field near the membrane surface were compared under different inflow velocity and obtained transient flow and turbulence intensity trends near the membrane surface with different inflow velocity. This article provided some data and theoretical foundation for further study of air gap membrane distillation system.