The mechanical properties at the interface of ABS/zeolite composites developed during hot plate welding were investigated using the lap-shear joint method. The self-bonding strength was proportional to one fourth the power of the welding time proposed by the diffusion models. The strength value of the ABS/zeolite system was lower than that of neat ABS due to the bad interfacial strength between the ABS and the zeolite, and the obstruction by the natural zeolite for the diffusion of the ABS molecular chains. As regards the fracture behavior, the welded specimens showed two types of failure; shear failure and tensile failure due to the stress concentration effect. When the lap shear joint samples were slipped by shear stress, plastically deformed ridges, which were the main feature of the welded specimens appeared on the fractured surface. Stress-whitening by crazing and local drawing was also observed at the edge of the bonded region on the deformed surface.