Abstract: Based on the detailed study on the current situation of non-marine sequence stratigraphy research,theauthor proposed a complete uprising-depressing cycle on a horizontal plane that can form four systemtracts,i.e.lowstand,lake extension,highstand,and lake contraction system tracts,with the western slopein the southern sector of Songliao basin(WSSB)taken as an example.As for an incomplete cycle,the temporal and spatial evolution of the system tracts is expressed as lowstand,lake extension,and highstand or aslake extension,highstand and lake contraction system tracts.Finally,the oil-gas accumulation patternaround the southwest slope of Songliao Basin is concluded.