The steady thermal stress problems under linear temperature load on upper surface in an Al1100/Ti-6Al-4V/SiC 2D-FGM plane four-side clamped plate are analyzed by the FEM. When the variation of the material composition in y-direction is linear, the plane thermal stress distributions with the changes of composition shape distribution coefficient mx and porosity coefficient Ax in x-direction are obtained. The results show that compressive stresses of the metal side reduce and the compressive stresses increase on the ceramic side with the increasing of the mx. Except for lower surface, when mx =0.5, the thermal stress values of the 2D-FGM plane plate are smaller than those of the 1D-FGM plate. Compared with the maximum thermal stress value of the 1D-FGM plate, that of the 2D-FGM plane plate reduces by 815MPa. The thermal stress curve surface has more and more obvious convex trend and has smaller thermal stress gradient with the increasing of the Ax, especially it is when =0.1~0.5, =0.2~0.5, and other places have no variation. By comparison with the minimum thermal stress of Ax=0.0, that of Ax=3.99 reduces by 47.3% at =0.3. The results provide more comprehensive and concrete foundation of calculation for design and optimization of the 2D-FGM plane plate.