RuO₂-based thick film resistor is widely used in thick film integrated circuits because of its good resistance stability and low temperature coefficient of resistance. In this study, the AS_f/SiO₂ composite and alumina ceramic were chosen as substrates, and the RuO₂-based thick films were fabricated on the two substrates by screen printing. The thermal mismatch between the thick film and substrates from 25℃ to 700℃ was analyzed by using the digital image correlation method, finite element method and XRD stress measurement method, and then the resistance-temperature characteristic for thick film was investigated. The results showed that the thermal expansion coefficient of the thick film was larger than that of AS_f/SiO₂ composites. The thick film fabricated on AS_f/SiO₂ composite substrate was suffered residual tensile, which was released at highStemperature. Thus, the distance between conductive particles was reduced, leading to the decrease of potential barrier resistance. Thick film prepared on AS_f/SiO₂ composite substrates presented negative resistance-temperature characteristic. On the contrary, the thermal expansion coefficient of the thick film was smaller than that of alumina. The thick film fabricated on alumina substrate was suffered residual compressive stress, which was also released at highStemperature. And then, the distance between conductive particles was rose, resulting in the increase of potential barrier resistance. The thick film prepared on alumina substrate exhibited positive resistance-temperature characteristic.. Keywords: RuO₂-based resistance film; AS_f/SiO₂ composite; thermal mismatch; residual stress