Large deformation and cutting vibration is an important problem in the process of manufacturing ultrathin blade of integral impeller, thus a non-uniform allowance process is used in this paper, which can reduce blade deformation and improve processing quality. Firstly, the influence of concentrated load both on the deformation of thin-walled structure and thickening structure wad analyzed. Then non-uniform allowance machining process of impeller blade was designed. Lastly, tool path was planned and processing experiment was done on the impeller. Results show that the process optimization strategy can effectively reduce milling vibration and milling deformation of ultra-thin blade, the max error optimization rate is 54.47% and the average error optimization rate is 52.57%, which is of significance to the actual production.