Aiming at the thermal mismatch caused by different Coefficients of Thermal Expansion (CTE) of each material in Chip on Board(COB), Digital Image Correlation (DIC) is used to measure the thermomechanical coupling effect in COB packaging structures, and effects of different type substrate are compared. The experiment results are compared with both the results of FEM simulations and the theoretical model. Experimental results reveal that DIC can successfully be applied to the analysis of the thermomechanical coupling effect and provide an availability consult to the design of MEMS apparatus.