Wenchang Depression, which is a Cenozoic dustpan fault depression stretching towards NE-SW trend and faulted in the south part and overlapped in the north part, is located in Zhusan Depression of Pearl River Mouth Basin in the north of South China Sea. Based on the organic geochemistry and fluid inclusion and basin simulation analysis, the source of oil and gas and the characteristics of hydrocarbon accumulation in Wenchang Depression are studied. The results show that the oil and gas from the middle deep lacustrine facies sapropelic source rocks of Wenchang Formation in the deep part of Wenchang B Depression migrate vertically along the South fault to the reservoir of Zhuhai Formation for accumulation. The oils from Wells W1, W2, W3 in the South and Well W4 in the north of Wenchang 19-1 structure are typical middle deep lacustrine oil. The oils from Wells W5 and W6 in the south of Wenchang 19-1 structure are mixtures from the middle deep lacustrine facies and shore shallow lacustrine facies source rocks of Wenchang Formation. The crude oil in Enping Formation of Well W14 in the north of Wenchang 19-1 structure, which came from the humic mixed source rock of shore shallow lacustrine facies of Wenchang Formation, was charged during 8.7-1 Ma. The crude oil in the third member of Zhuhai Formation of Well W15 in the central area of Wenchang A Depression was mainly from the source rock of Enping Formation, and the oil and gas filling time was about 4.1-0.2 Ma. [ABSTRACT FROM AUTHOR]