Paleogeotemperatures of the Tarim Basin have been determined on the basis of the degreeof thermal alteration of organic matter and its thermal history. Evidence shows that thepaleogeothermal gradient for this area is generally low: 3℃/100 m for the Paleozoic group and2.5℃/100 m for the Mesozoic group. The establishment of a geological paleogeothermal modelmakes it possible to gain a deeper understanding of oil-generating processes. The peak of oil-generation is generally set at a depth of 5000-6000 m. Higher pressure within the strata isfavourable for the preservation of oil at great depths. Organic matter enclosed in carbonateminerals is believed to be another important source of oil. It is suggested that there may be largereserves of natural gases in the area studied with a rough estimation of about 0.6×10~4billion m~3. Paleogeotemperatures of the Tarim Basin have been determined on the basis of the degree of thermal alteration of organic matter and its thermal history. Evidence shows that the paleogeothermal gradient for this area is generally low: 3 ° C / 100 m for the Paleozoic group and 2.5 ° C / The establishment of a geological paleogeothermal model makes it possible to gain a deeper understanding of oil-generating processes. The peak of oil-generation is generally set at a depth of 5000-6000 m. Higher pressure within the strata isfavourable for the preservation of oil at great depths. Organic matter enclosed in carbonateminerals is believed to be another important source of oil. It is suggested that there may be largereserves of natural gases in the area studied with a rough estimation of about 0.6 × 10 ~ 4billion m ~ 3.