Abstract: Shaximiao formation of piedmont zone of Longmen mountain is the main gas producing layer of Sichuan basin, which is lacking of research on its reservoir development features and controlling factors. Based on cuttings, core observation and experimental analysis, the reservoir development features and controlling factors in the research area have been confirmed. The results show that the sandstones of Shaximiao formation in piedmont zone of Longmen mountain are mainly composed of lithic sandstones and lithic quartz sandstones. The composition maturity of sandstones is generally low, and the clastic content is characterized by low feldspar and high clastic. The reservoir pores are mainly primary pores and dissolution pores, with poor physical properties and poor connectivity. Compaction and cementation are the main factors of reservoir porosity reduction, while dissolution is the main constructive diagenesis in this area.