Abstract: An on-line real-time system for measuring thermal expansion coefficients of conductive thin films was developed,which was combined with the micro-imaging and digital image correlation method.The relation curves of thermal expansion coefficients of SnO2 thin films with the temperature were determined and the stress changes between the film and substrate could also be obtained further by the system.The results show that the system accurately determined the anisotropy of thermal expansion of the SnO2 thin film and ceramic substrate.According to the experimental results and existing theories,the maximum stress between the films and substrate and the changes of the stress inside the substrate could be calculated.