Middle-shallow crude oil is mature and light with the characteristics of low-density，low-viscosity，low-chill point，waxy，low-sulfur and colloid in No.2 Structural Belt of the Nanpu Sag，which is not biodegraded basically. Based on the geochemical characteristics of source rocks and crude oil，the source rocks are divided into Type I and TypeⅡ，which are respectively distributed in Es3+2 and Ed. The Type I source rock is better than the TypeⅡ. The crude oil can be divided into Type A，Type B and Type C. Type A oil has lower gammacerane content，while Type B oil has higher gammacerane content. The regular sterane C27，C28，C29 of the three types of crude oil are characterized by the typical features of“√”，“L”and “V”. The kerogens are from both lower hydrobiont and higher plants，which are formed in lacustrine environment characterized by weakly oxic to weakly reducing fresh water. Type A and Type B crude oil are respectively related to Type I and Type Ⅱsource rocks，and Type C of crude oil is from both Type I and TypeⅡsource rocks. On this basis，the source of different crude oil could be determined，and according to the relation of the source and the reservoir，the model of oil and gas migration and accumulation in middle-shallow reservoirs was established. The faults act as paths for upward migration of deep oil and gas. The crude oil types and petroliferous property in both side of the faults are controlled by fault sealing. Abnormal high pressure in deep stratigraphy provides driving force for the migration of deep oil and gas. The relationship between source rocks and faults influences the distribution and type of the middle-shallow crude oil.