The finite element model is built by ANSYS, and the distribution of stress is studied. The stress intensity of each layer is computed by Tsai-Wu stress intensity standard. The value computed by Tsai-Wu stress intensity standard under given loads are smaller than 1, and the GFRP bridge deck is in a safe state. The first ply failure is also studied, and the result shows that the first ply failure value is determined by the webs when the webs are very thin. Other circumstances the value is determined by the size of the top and bottom plate. The material utilization is the highest when the thickness of the bottom is equal to the whole webs and a little thinner than the top plate.