This study examines the transverse bridge stresses of the link slab for the disaster such as the structural crack in the simply-supported steel-concrete composite bridge. The link slab's deflection and stress distribution functions are determined using linear elastic theory and the partial differential equation of the plate. A nonlinear finite element model is also established based on actual bridge load testing. The theoretical solution， finite element solution， and real bridge load test results are compared to validate the theoretical solution and finite element. The study shows that the upper face of the link slab at the end of the steel girder experiences the maximum tensile stress in the direction of the transverse and longitudinal bridge. The paper also explores the impact of the link slab area size on the peak stress in the transversal bridge direction. Results reveal that smaller longitudinal beam spacing and longer longitudinal beam end length increase the maximum transversal tensile stress of the link slab， causing the link slab to develop cracks before reaching the design load. Therefore， for a jointless bridge with a small longitudinal girder spacing and a long girder end length， only calculating the mechanical performance in the longitudinal bridge direction yields dangerous calculation results. It is advisable to consider the transverse bridge direction stress according to the method in this paper.