Abstract: An experimental study on the boundary layer flow and near wake behavior of a NA-CA0012 airfoil was conducted in the water tunnel,with the primary interest in the evolution of coherent structures at different angles-of-attack up to 15°and Reynolds number of 8200.It is found that the separation point,as well as the location of vortex roll-up,moves toward the lead-ing-edge of the airfoil as the angle-of-attack increases,and the size of reserve flow region also in-creases as the angle-of-attack increased.When a laminar separation bubble is formed at some an-gles-of-attack,the three-dimensional deformation of the roll-up-vortices,as well as vortex par-ing,is observed around the reattachment point.