Siwujiazi oilfield of Songliao Basin, located in the City of Gongzhuling in Jilin Province, is a part of Yangdachengzi Anticline at Southeast upwelling area. The reservoir of oilfield is mainly composed of Quantou Formation in Lower Cretaceous, which is deposited in dry and oxidized environment at Late Cretaceous. The source provenance area is central ancient-uplift. The reservoir is mainly composed of lithic arkoses and some lithic feldspathic sandstone, feldspathic litharenite sandstone. Based on the analysis of single well facies, the main facies marker include sedimentary structure and granularity distribution reflecting the traction current sedimentary mechanism. Through the analysis of facies marker, the reservoir is meandering river. There are 4 microfacies, i.e. meandering point bars, crevasse-splays, natural levees and flood plains. The vertical combination of the river is point bars-natural levees-crevasse-splays-flood plains from below to top. In setting up the logging facies, the microfacies of 136 non-sampling wells were identified, and then the inter-well sedimentary microfacies were forecasted by applying sequential indicator simulation. The research shows that there are two meander rivers stretching from NNE to SSW and the 6 and 7 layers of Quantou Formation which have the character of point bars. This study is an important foundation for next oilfield development.