Abstract: The coal measure strata in the Upper Permian Longtan Formation serve as important source rock in Sichuan Basin, and good oil and gas displays have commonly been observed during well drilling. However, the previous study work only focused at the level of source rock evaluation, and there was a lack of evaluation on geological conditions of coal measure gas. Based on the comprehensive analysis of core measurement data and well drilling data of Longtan Formation in Da’an area in Western Chongqing, the distribution characteristics, source rock characteristics, reservoir properties, gas bearing property, and preservation conditions have been studied, which support to determine the geological conditions and exploration prospects of coal measure gas in Longtan Formation in Da’an area in Western Chongqing. The study results show that Da’an area was located in the favorable sedimentary zone during the deposition of Longtan Formation coal measure strata,with wide distribution area, thin single layer thickness, and concentrated coal accumulation area; The coal rock is dominated by primary structure, medium-low ash content, and well developed cleats and pores; The coal rock has good gas bearing property, high free gas content,high porosity, high formation pressure and high gas content; The roof and floor of coal rock are mainly composed of mudstone, showing good preservation conditions. The comprehensive evaluation indicates that the coal measure reservoir in Longtan Formation in Da’an area has good porosity and permeability, high gas content, and moderate burial depth, which shows great exploration prospects.