Abstract: In recent years, a major discovery of oil and gas exploration in ultra-deep clastic rocks has been achieved in Linhe Depression of Hetao Basin by increasing the geological understanding of late oil and gas accumulation in deep ultra-deep clastic rocks.Based on the thermal simulation of Paleogene source rocks, drilling and logging data and analysis of reservoir formation and accumulation evolution, three important geological understandings are mainly formed.（1）High-quality source rocks rich in resinite ( terrestrial ) and algae ( aquatic ) are developed in the Paleogene in the northern part of Linhe Depression. The source rocks begin to generate and expel a large amount of hydrocarbons in the low evolution stage, which has the characteristics of high hydrocarbon generation intensity and wide hydrocarbon generation window. The ultra-deep thermal evolution degree of the trough area is relatively high, and the potential of oil and gas resources is large.（2）The braided river delta deposits are developed in the shallow slope of the far source water, and the sand bodies are widely distributed. Affected by weak diagenesis such as low geothermal temperature, late deep burial, high quartz content, weak compaction and weak cementation, a new mechanism of reservoir formation and storage is put forward, which is dominated by weak diagenesis and pore preservation, and superimposed by epigenetic ultra-high pressure transformation and fracture expansion. The reservoir has good physical properties and greatly expands the space of ultra-deep oil and gas exploration. （3）A new understanding of conventional oil and gas accumulation is put forward, which includes early filling in hydrocarbon generation period, continuous subsidence, deep buried thermal evolution, accelerated hydrocarbon generation and expulsion, continuous filling to form supersaturated and ultra-high pressure oil and gas reservoirs, and natural fracturing of reservoir-source interaction bodies by ultra-high pressure, forming fracture-pore connectivity, source-reservoir convergence and continuous large-area distribution, which effectively improves the exploration potential of ultra-deep conventional oil and gas reservoirs.The above studies show that the ultra-deep oil and gas accumulation conditions of the Paleogene Linhe Formation in the northern part of the Linhe Depression are superior. Combined with the large area of favorable exploration areas, it shows a good exploration prospect. At the same time, it further enriches the theoretical understanding of the late oil and gas accumulation of ultra-deep clastic rocks. It has important guiding significance for the exploration of similar basins, especially the ultra-deep source of 10,000 meters.