Abstract: Fault and unconformity are important conduits for hydrocarbon migration and accumulation.However,the difference of fluid activities between these two conduits is not well constrained.In this paper,we address this issue based on a case study in the central Junggar Basin,mainly by the analysis of mineralogical and petrological records of fluid activities.Resultsshow that the fluid activity in the fault zones is complex.The fault acts as good conduits for hydrocarbon migration in an episodic style during activating period,with the fluid source mainly coming from deep petroleum fluid and meteoric water.This is similar to the case in the reservoir underlying the unconformity.In contrast,the fluids activating in the reservoir overlying the unconformity are different and relatively simple,i.e.,petroleum fluid.Generally,the intensity of fluid activity in fault zones is stronger than that in unconformity zones.The cross of fault and unconformity is the most favorable for the activity of petroleum fluid.Along the distance to unconformity,the fluid activity decreases.These results provide scientific foundation for regional petroleum exploration,and can also be referred by similar studies in other cases.