Abstract: The formation pressure profile of western Qaidam basin is divided into 3 types and characterized by those as follows: TypeⅠ appears the increase of formation pressure with depth by normal pressure section and abnormal overpressure section; Type II is similar to TypeⅠexcept for pressure drop point in the abnormal overpressure section; Type Ⅲ: the trend of the formation pressure changing with depth occurs in single section, namely, the pressure changes normally nearby the hydrostatic pressure line. The formation pressure profile of TypeⅠ mainly appears in settling area, that of Type Ⅱ in fault or fracture developing area of it, while that of Type Ⅲ in denudation area. The distribution of oil and gas fields of the Tertiary in western Qaidam basin is mainly related to Type Ⅱ and Type Ⅲ profiles with pressure drops. And the main reason is probably that the pressure drops could lead to the large scale migration of oil and gas in condition of coexisting oil, gas and water