Abstract: In Harbin No.6 Pharmaceutical Factory, the thickness of an external transverse brick wall of a workshop building?needs to be changed from 490mm to 620mm due to functional requirement.In order to be harmonious with the adj a?cent?office?buildings ornament, dry- hanging- stone curtain wall must be put up outside the external wall.The prestressed frame with?cantilever should be checked and strengthened, for the additional loads caused by thickened wall and curtain wall are not?considered in the original design.Calculation shows that all columns and beams except cantilever beams still meet the relative?design standards in the condition of the increased loads, so only the cantilever beams need strengthening.It is proposed that?the idea and method to increase resistance, reduce crack and deflection of the cantilever structure by setting up a post-constructed concrete wall between the cantilever beam of the foundation and that of 1st floor of the frame to form a deep beam?with a column on one side.It can be served as reference for design of similar strengthening and remodeling project.