The invention discloses a complex metal surface numerical control progressive strengthening method which comprises the following steps of selecting a numerical control progressive strengthening method, selecting the proper numerical control progressive strengthening method according to the actual machining conditions and requirements; selecting the numerical control progressive strengthening process parameters, selecting the proper numerical control progressive strengthening process parameters according to the selected numerical control progressive strengthening method, the shape size of a metal piece and the material performance; carrying out the numerical control progressive strengthening, specifically, adjusting the numerical control progressive strengthening technological parameters based on the appearance of the metal piece to enable the technological parameters to adapt to the actual surface contour of the metal piece; annealing the metal piece, carrying out the stress annealingon the reinforced metal piece, wherein the annealing parameters are determined through an experimental method, and selecting the optimal parameter combination enabling a nanometer gradient structureto be stable. According to the method, the nanometer gradient structure is prepared on the complex surface of the metal piece through the complex metal surface numerical control progressive strengthening, the surface self-nanocrystallization is achieved, and the comprehensive service performance of the metal piece is improved.