Abstract: Experimental research was conducted to investigate the rotation effect on the film covering area, which is important to comprehend the mixing process of the coolant flow and the hot gas over the high pressure turbine blades. A simple flat surface with a 30° inclined film hole was positioned parallel to the hot main stream and different rotation orientations were selected to simulate the blade pressure or sides. Liquid crystal was used to supply the temperature field information over the blade surface and the average adiabatic effectiveness of the area adjacent to the film hole was selected to measure the cooling effect. Rotating speed varied in 0, 300, 500, 800 and 1000 r/min. It was found that the film trajectory could bend under the rotation condition. With the increase of the rotating speed, on the pressure side the film trajectory inclines centripetally firstly and centrifugally at last. On the suction side, the film trajectory bends centrifugally. As the momentum flux ratio kept constant, the increase of the density ratio could lead the film trajectory to incline more centripetally on the pressure side. But on the suction side, the trajectory bends more centripetally.