There are many research results about the Middle Permian Qixia Formation in the northwestern Sichuan Basin, however, the great differences in the cognition of the sedimentary facies characteristics and models have seriously restricted its exploration. In order to deepen the understanding of the characteristics of sedimentary facies of Qixia Formation and improve the efficiency of hydrocarbon exploration, based on the data of core description,field profile measurement, logging and seismic data, the characteristics of sedimentary facies were studied. The maps of sedimentary facies of the early and late Qixia Formation were compiled. It is considered that Qixia Formation mainly developed three types of sedimentary facies including open platform, platform edge, foreland gentle slope,as well as six types of subfacies and 11 types of microfacies. According to the relative sea level changes, the distribution characteristics of the sedimentary microfacies, subfacies and facies and their sedimentary evolution rule, the evolution model of gentle slope platform of Qixia Formation was established, which coordinates the relationship of carbonate platform model with carbonate slop model.