The study endeavors to ascertain the gas and oil distribution laws of the upper-source and lower-reservoir petroliferous basin. Initially, drawing on the investigation into the gas and oil vertical downward migrating conditions and positions, determining gas and oil expulsion area of source rock, gas and oil vertical downward migrating area and transporting fault distribution area, which are superimposed to determine gas and oil vertical downward migration region. Combining the determination of inner fault convex ridge system, establishes a set of gas and oil vertical downward migrating favorable location prediction method. This methodology is subsequently employed in the examination of Q1 (the 1st member of Formation Qingshankou) within Sanzhao Sag situated in the Songliao basin. The findings reveal the favorable locations of gas and oil vertical downward migrating from Q1 source rock to FY (Fuyang oil layer) distribute in most parts of gas and oil vertical downward migrating area within Q1 source rock. The gas and oil vertical downward migrates into FY through the above positions, then accumulates in Zhaozhou, Yushulin, Songfangtun and Shengping nose structure through lateral migration. This aligns with the observed distribution of gas and oil of FY. It is feasible to use this method to predict favorable locations for vertical downward migration of gas and oil.