Abstract: The hydrocarbon pathway systems in the Mahai-Nanbaxian area have been established based on the characteristics of connective sandbody , fault and unconformity , and then their contributions to hydrocarbon accumulation were evaluated.The results show that the connective sandbody , fault and unconformity are mainly developed in the Mahai-Nanbaxian area.They can be combined to form three hydrocarbon pathway systems : fault single-pathway system , faultsandbody complex pathway system and fault-unconformity complex pathway system.These hydrocarbon pathway systems dominate the reservoir type , hydrocarbon accumulation phases , hydrocarbon migration distance , hydrocarbon spatial distribution and source reservoir cap combination , which result in the diversity of oil-bearing series and reservoir types in the Mahai-Nanbaxian structural belt.