Abstract: In order to explore the influence of self-drilling self-tapping screws (parameters such as head type, material, diameter, threads per inch, washers, etc.) and connected materials (edge distance) on the failure modes and shear bearing capacity of the connections in enclosure systems, an experimental study of mechanical properties was conducted on 93 groups of specimens of two types of joints connected by carbon steel and stainless steel composite screws fastened to 445J2 stainless steel plates based on steel substrates. The failure modes of these two types of joints were analyzed, and the parameters influencing the shear bearing capacity of the joints were revealed. The results showed that both types of joints exhibited a failure mode where the self-drilling self-tapping screws, 445J2 stainless steel plates, and steel substrates jointly bear the external load. This was followed by progressive damage and deformation at the engagement between the screws and the 445J2 stainless steel plates, ultimately leading to shear failure of the stainless steel plates. The screw holes showed an enlarged failure mode along the loading direction. The parameters of self-drilling self-tapping screws had a significant impact on the shear bearing capacity of the joints. The peak shear bearing capacity achieved the maximum improvement of 48.4% when different types of screw heads were adopted. In contrast, the edge distance (margin) showed no clear trend in its effect on the shear bearing capacity of the connection nodes, with the peak shear capacity varying only by 9.5% at the highest.