By the analysis of samples from SK-1, high content gammacerane was detected in the strata from the top of the 2^nd and 3^rd member of Yaojia formation to the bottom of the 2^nd member of Nenjiang Formation, Songliao Basin, which suggesting that water stratification occurred during this period. Compared with the total organic carbon(TOC) and δ¹³C_orgdata, the high contents of gammacerane correspond well with the high values of TOC and the negative values of δ¹³C_org. This correspondence suggests that water stratification led to the anoxic environment in the Songliao Paleo-lake, which contributed to the preservation and deposit of organic matter during the sedimentary period of Nenjiang Formation. It is inferred that the water stratification is related to the marine incursion in the Songliao Basin.