Abstract: The prestressed continuous steel-concrete composite beams have lots of advantages, such as high bearing capacity,small deformation and so on,and have been widely used in engineering as a new transverse bearing component. The calculation of capacity and the deformation analysis on a negative-moment region is the key to the design of the prestressed continuous steel-concrete composite beams, and current corresponding specification is still blank. Thusly, it is necessary to research the stiffness, the deformation and a bending capacity formulation. The bending stiffness of the cross-section of the composite beams was determined, and the bending capacity in the state of an elastic limit was calculated with the method of a conversion section principle by the introduction of the degree coefficient of concrete participation in tension. Besides, the bending capacity of composite beams bearing a negative bending moment in the ultimate limit state was deduced by using simplified plasticity theory. The research shows that it is very useful to improve the rigidity of the cross section and slow cracking of continuous composite beams. It turns out that the calculation values are in a good agreement with the experimental results, which meet the engineering accuracy.