Abstract: In order to study the flow field characteristics of impingement-effusion cooling,a kind of impingement-effusion cooling structure was designed,the flow field characteristics of it was studied by PIV(particle image velocimetry).It was found that the flow characteristics between impingement plate and effusion plate is very complex,and the size of eddy between impingement plate and effusion plate is different with the change of blowing ratio.On the side of effusion film,the flow from effusion hole will penetrate gradually main flow when blowing ratio is increased,that destroys the effusion film.There is a pair of "kidney eddies" on the vertical section of the outlet of effusion hole,and the "kidney eddies" will moves into the main flow when the blowing ratio is increased.