The west slop in Songliao basin abounds in oil sand resources, whose formation has a close relation to the geology, structure and oil-gas enrichment in Songliao basin. Large quantity of sand body provide a reservoir for crude oil, faults and strata erosion form the channel for oil to migrate, and the compact mudstone keeps crude oil from volatilizing, oxidizing and biodegradation. The abundant oil sources in Songliao basin are another necessary factor to form the oil sands. This paper presents that the Tumuji oil sands are largely controlled by sedimentary facies, reservoir-caprock, local peak, lithological change uparwards, surface hydrological dynamics and  gross oil-gas migration quantity.