This paper presents results of the modeling of the temperature distribution in a chip of thin film gas sensor, operating at high temperatures (150-1000o C), required to provide high sensitivity and selectivity to target gases. Analysis of thermal regimes of such chip was carried out on the base of model of plate with local source of heat. It was found that substrate heat conductivity is most influencing parameter, determining both temperature distribution in chip and also the electrical power consumption decreasing. The example of realized chips designed in accordance with results of modeling is presented. The results of modeling are compared with experimental data.