The 304 stainless steel/Q245 carbon steel explosive welding interface was taken as the research object to systematically detect the structure heterogeneity and its effect on the shear behavior in engineering application. First, characters on the transverse section and longitudinal section of the welding interface were detected. And based on the non-equilibrium theory, the mechanism of the heterogeneity on the welding interface has been explained. Furthermore, taking into account the wavy structure and its undulance along the detonation direction, shear performances varied with orientation angles were measured according to the national standard (GB/T 6396-2008). Finally, the morphologies of fracture surface were observed by SEM to recognize the influence of welding interface structure on the failure mode. Results show out that the explosive detonation pressure fluctuation is the fundamental cause of the inhomogeneity on the welding interface, the failure mode and cracks developments were determined by the undulation characters of wavy interface. Besides, an optimal orientation angle, on which samples have the maximum shear strength, was revealed. All of them can be used to guide the engineering application for explosive welding plates.