The invention discloses a method capable of avoiding buckling of forge pieces in the length direction and reducing residual stress of high-slenderness-ratio arc-shaped fillet opened aluminum alloy forge pieces. A cold compressing die is adopted for implementing the method and the method comprises the steps that A, the forge pieces are subjected to cold compression within four hours after solid solution heat treatment; B, the forge pieces are put into the cold compressing die; C, a steel plate is longitudinally arranged in the position, corresponding to a fillet, of the non-fillet face, and then cold compression deformation is conducted; D, a new steel plate is placed on each of the two sides of the part subjected to cold compression, the overlap amount of the steel plate and the indentation of former cold compression is 30%-50%, and then cold compression deformation is conducted again; E, the step D is repeated until cold compression deformation of all zones of the non-fillet face is completed; F, finally, the middle of the non-fillet face is subjected to cold compression again; and G, overall cold compression is conducted again after segmented cold compression is completed and the overall cold compression is controlled by tonnage. By adopting the method, the uniformity of the appearance of the forge pieces can be ensured and the evenness of the cold compression deformation amount of the forge pieces is improved.