Abstract: In this paper, it is proposed that the plane strain problems in plasticity can be solved with the standardized upper bound modes and the corresponding solutions. As an illustration of the above proposal, the standardized upper bound modes and the upper bound solutions for the compression of a strip between flat dies, indentation of a semi-infinite medium and a semi-infinite block of finite depth resting on a plane foundation by a flat die, die forging and compound extrusion are listed. It shows that the standardized upper bound solutions can make the upper bound solutions generalized, and easily and quickly obtained with a quite small over-estimate, and that the outline of the standardized upper bound modes is similar to that of the slip line field. The similarity of the two makes it possible to find the real slip line field of the corresponding problem and to identify the feasibility of presupposed slip line fields with the standardized upper bound mode.