Abstract: According to the lithological association, structural configuration and the lithomechanical analyses, the author distinguished the synclines in Southern Sichuan into three kinds of reservoir space, that is, the gapping fissure networks in syncline bowls, the decollement in deep syncline bowls and the connate connected pores in the low pervious beds,The paper further discussed the three development stages of synclinal fissure reserovirs,which are the early congregation stage, the reformation stage and the stable stage，and pointed out that it is the synoline that is the new natural gas exploration target in Southern Sichuan.

Key words: Natural gas exploration, Syncline, Southern Sichuan