Abstract: The aerodynamic design features of the propeller have been analysed at first.According to the analytical results and the modern advancements in propeller technology,the specifications of its expected modification have been proposed.In its overall design the important parameters have been determined.The principles of optimization and the version selection are outlined.From the comparison between the wind tunnel testing results of both scaled models of the propeller and its modification,it is concluded that the modification is a great success.Its static thrust and takeoff climb efficiency are increased by 13 8% and 8 76% respectively.Its cruise efficiency and noise level are also slightly improved.All they exceed the expected ones.