The bridge deck of steel-concrete composite girder bridge with combined slabs is composed of precast slab and cast-in-place slab. The precast slab can provide casting template for cast-in-place slab, which saves the formwork erection process and accelerates the construction progress. Due to the difference of loading ages between precast slab and cast-in-place slab, shrinkage and creep of concrete will cause stress redistribution among cast-in-place slab, precast slab and steel girder. In this paper, the (40+55+40m) steel-concrete composite girder bridge of an elevated expressway is taking as the engineering background, the finite element analysis results show that the shrinkage and creep stress of composite slabs is about 0.82~0.97 times that of cast-in-place composite slabs, and the stress of steel girders after completion is about 0.80~0.94 times that of cast-in-place composite slabs, combined slabs have obvious "inhibition" effect on shrinkage and creep of concrete.