Abstract: Due to differences in tectonic movement and sedimentation, multiple types of abnormal pressure were developed in the Junggar Basin. According to their forming mechanisms, the abnormal pressure systems of the whole basin may be divided into four types. In the center of the basin,diagenesis and hydrocarbon generation are the key factors resulting in overpressure. Undercompaction and uplift controlled the development of abnormal high pressure in the south and in east of the basin, strong lateral compressive stress from Bogeda Mountain brought on overpressure in a large area. Besides, abnormal low pressure was found in Junggar basin for the first time. Different from wide distribution of abnormal high pressure, low pressure is mainly limited in Wucaiwan Depression at front of Kelameili Mountain. This low pressure belt is related to deep geosyncline of foreland basin formed in Carboniferous and Permian Periods.