In order to master the temperature stress variation of lightweight composite bridge decks and to avoid interlaminar failures between TPO-UHPC， the thermal expansion coefficient and elastic modulus of TPO materials were investigated by strain gauge method and ultrasonic method respectively; the interface temperature stresses of the composite pavement system were calculated by using ABAQUS finite element software. The parameter sensitivity analysis was performed on the main factors that affect the interface temperature stress of the pavement system. The effects on interface thermal stress between TPO-UHPC were discussed， referring to thermal expansion coefficient ratio， TPO thickness and construction temperature. The experimental results show that the thermal expansion coefficient of TPO is much larger than that of cement-based materials， and the elastic modulus of TPO decreases with the increase of temperature. The simulation results show that，under the condition of uniform temperature， the interlaminar shear stress and the normal tensile stress decrease with decreasing the expansion coefficient ratio and the thickness of the TPO layer; the interlaminar shear stress plays a more dominant role than the normal tensile stress in the pavement system. The influences of construction temperature on the interlaminar stress of TPO-UHPC are different for high and low temperature. It is possible to reduce the interface temperature stress amplitude by a suitable construction temperature and TPO thickness.