Abstract: To meet the requirements of renovating an old industrial building, it is necessary to conduct a strengthening design for a non-standard H-shaped steel cantilever beam. Firstly, a numerical simulation of the original beam was performed using ANSYS software. The simulation results indicated that after the renovation, the beam would not develop plastic or creep zones; however, the deformation at the free end of the beam was excessively large. Therefore, the ultimate goal of the formulated strengthening measures was to reduce the deformation at its free end. This paper conducts numerical simulation and calculation analysis on three different steel beam reinforcement schemes. The results show that these schemes have distinct differences in restraining beam deformation. It is verified that adding steel plates on the web achieves little effect and only slightly reduces the beam end displacement. By contrast, welding steel plates on the outer flanges delivers outstanding performance, cutting the beam end displacement by 77%. The results demonstrate that reinforcement position exerts a decisive impact on strengthening effect. It provides reliable data support and practical reference for reinforcement design and scheme selection of similar non-standard H-shaped steel beams, and effectively enhances structural bearing safety and service performance.