The invention provides a method for jetting, eroding and processing a downhole steel ball, an abrasive jet mode is adopted, the stuck steel ball and positions where the steel ball is in contact with a ball seat are downwardly jetted and eroded along a shaft axis, an internal drift diameter of the ball seat is enlarged or an internal diameter of the steel ball is reduced through erosion, and therefore constraint of the ball seat on the steel ball is released, and the steel ball can be returned to the ground by itself under the support of downhole liquid. Working efficiency and technology safety level can be largely improved by the method.