In this paper, the photoelastic technique and finite element method were employed to investigate the interfacial stresses induced by thermal loading in bimaterial structures. By observing the photoelastic fringe patterns, in comparison with those theories developed by other investigators, severe temperature and stress gradients were found across the specimens’ heights. The maximum fringe order near the interface was six times that near the top surface of the photoelastic material when the temperature was raised to 65 °C. Furthermore, for the bimaterial structures, differences were found between measured stress fields as a result of increasing and decreasing temperature differences.