This study aimed to address the reduced durability and corrosion issues of traditional multi-span simply supported beam bridges caused by concrete cracking and design flaws. A novel steel-concrete composite flat slab continuous bridge deck structure (referred to as the flat slab continuous) is proposed, which effectively prevents surface cracking by keeping the surface concrete to compression under positive bending moments. With a three-span simply supported beam bridge as the engineering context, this research conducted finite element numerical simulation on the deformation and force characteristics of the flat slab continuous and the traditional tie-rod continuous simply supported beam bridges under various vehicle loads by establishing a detailed finite element model. The results indicate that under mid-span load and off-center load, the maximum tensile stresses for the traditional tie-rod continuous were 1.16 MPa and 4.50 MPa, respectively, in contrast, the upper surface of the novel flat slab continuous was in compression. Furthermore, comparative analysis shows that under overload and anti-tipping conditions, the deflection difference at the mid-span cross-section of the main beam for the flat slab continuous simply supported beam bridge was reduced by 24.50% and 13.43%, respectively. The findings demonstrate that the flat slab continuous can effectively prevent the occurrence of deck cracking and has a significant advantage in improving the bridge's anti-tipping performance, offering a new perspective for the design and retrofitting of multi-span simply supported beam bridges.