Features of the petroleum fluid activity in the Hongshanzui- Chepaizi fault zone，including the main faultbelt and its wall rocks，of the Junggar Basin are described by means of geochemical approaches of trace elementsand fluid inclusions．It is showed that the fault acted as a good conduit for petroleum fluid migration during theactivating period．The generated hydrocarbons were charged to wall rock reservoirs along the shearing zone，and the upper wall of the fault is relatively m ore favorable for petroleum accumulation compared with the lowerwal1． Two critical moments for petroleum charge were suggested，which could be further divided into manysub—periods．Oil and gas were m igrated periodically in an oil—gas—water—mixed phase in the fault zone．