In order to reveal the mechanical properties of the adhesively-bonded join between fiber-reinforced polymer（FRP）bridge deck and steel beam, the mechanical behavior of adhesive joints under different tensile/shear combination loads was studied experimentally, including ultimate failure loads, failure modes, stiffness as well as strength failure criterion. Considering the mechanical characteristics of adhesively-bonded joint, six different load combinations of tensile and shear were achieved through a special test device. The results showed that under the pure shear loading, the failure of adhesive joints occurring in the adhesive layer was a cohesive failure at a location close to the steel support. Under the tensile and four combined loading conditions, the failure mode was the combination of fiber breaking (or FRP delamination) and interfacial adhesion failure between the FRP sandwich deck and adhesive layer. Load-deformation curves indicated that the non homogeneous characteristic of the adhesive layer was evident, which induced the eccentric loading on the adhesive joints and stress redistribution during the test process. According to the vectorially separated tensile and shear stress, the tensile-shear strength failure criterion of the adhesive joint was addressed.