Abstract: Since the 1980s, some scholars put forward a new point of view that transgression had taken place in the Cretaceous in Songliao basin. Discovery of such facies fossils and minerals as sea creatures, calcareous nannofossils, glauconite, etc. is considered to be the main evidences of that transgression event. Combined with the latest research results of lithofacies palaeogeography in Songliao basin, the transgression event in Songliao basin is worth to question. All the evidences of inconsistence of global sea?level change with the high water level of lake transgression, the discovery of Yushu river system in eastern Songliao basin and geochemical data show Songliao basin was an enclosed lake basin in the Cretaceous. The discovery of sea creatures and glauconite, etc. just indicates the saline effect of water in this ancient lake basin, being still a lack of valid evidences of such a transgression event