Abstract: The shallow natural gas bearing reservoir of the Longquanshan tunnel of Chengdu metro is the sand? stone reservoir of Jurassic Shaximiao formation, and its distribution characteristics are affected by the Wolongmiao syncline, Longquanyi anticline and Ma′anshan fault structure. Based on an analysis of the geological drilling test, it is found that the shallow natural gas of Longquanshan tunnel has close correlation with sandstone bed, natural gas migrates from the sandstone reservoir and fractured zone of fault to the tunnel excavation space, and the preventive measures are designed based on two areas of high gas risks and three areas of low gas risks; the gas is mainly distributed at the place nearby the three geological structures, especially the gas concentration is high at the deep sandstone stratum of the west wing of Wolongmiao syncline.