Flexible functional layer of asphalt sands setting between concrete pavement slab and base can change the contact state of different layers and reduce the friction coefficient between slab and base and the thermal stress of pavement slab can be decreased. This functional layer can also protect the base from void disease produced by infiltration and erosion of rain water and snow water. This paper mainly focuses on the impact of parameters variation of contact state of pavement structural layer, slab length and flexible asphalt functional layer thickness and modulus for concrete pavement thermal stress to provide some basis for the selection of flexible functional layer of concrete pavement structure. Calculation results show that interlayer friction coefficient has relatively obvious effect on thermal stress of pavement structure; setting a functional layer can reduce the slab thermal stress evidently. Slab thermal stress and base thermal stress increase non-linear with the growth of slab length. The thickness variation of the functional layer has a slight impact on the concrete slab thermal stress. The higher the modulus of the functional layer is, the greater the slab thermal stress is.