There are a lot of theoretical studies of conventional and unconventional oil and gas. However，the study of the relationship between conventional and unconventional oil and gas is still rare. In view of this，from the aspects of formation time，space distribution and the amount of oil and gas resources，research results of conventional and unconventional oil and gas were summarized；the problems in the research of conventional and unconventional oil and gas were pointed out，and the development trend of the conventional and unconventional oil and gas was analyzed. The results show that there are three types of relationships between conventional oil and gas and unconventional oil and gas characterized of reservoirsource contact：reservoir getting tight prior to hydrocarbon charging，reservoir getting tight after hydrocarbon charging and reservoir getting tight contemporaneous with hydrocarbon charging. Conventional oil and gas are mainly distributed in the higher part of the structure，and unconventional oil and gas are generally distributed in the center of the basin or the general slope. The relationships between conventional and unconventional oil and gas resources are consistent with those in the triangle diagram of oil and gas resources distribution. But there are still problems for the conventional and unconventional oil and gas：the formation time，the transition belt of oil and gas distribution，the relationship of oil and gas resources between different structural units and the determination of unconventional oil and gas boundary. In the future，more attention should be paid on the researches of whole process of hydrocarbon generation and expulsion，fine-grained sedimentology，oil and gas resources evaluation and accumulation of oil and gas.