This paper studies the shear stress at the connection joints of a segmental prefabricated-composite box girder with corrugated steel webs. As the shear bearing capacity of the top and bottom concrete flanges of the segmental girder is weaker than that of an integral girder, this study focuses on the shear behavior at the combined joints of bridge segments under vehicle loads. The effects of concrete shear connector, concrete friction, the adhesive layer and steel web on the shear bearing capacity are considered. Laboratory tests were carried out for the segmental girder and an integral box girder as a reference. The structural behavior of the test girders' joint surfaces was also simulated through finite element analysis. Results show the shear bearing capacity formula for concrete box girders from the AASHTO Standard can be factored by a reduction coefficient of 0.9 to achieve a more accurate calculation. It shows that the modified formula can accurately reflect the shear stress variation trend of composite joints, and the percentage differences between the calculated values using the modified formula and those from experimental tests and simulations are both within 5%.