Abstract: The Whole Petroleum System theory establishes the unified accumulation mechanism, enrichment regularity and geodynamic control conditions of conventional and unconventional oil and gas. Tight oil and gas are crucial components of the Whole Petroleum System. This paper reviews the development history of tight oil and gas, looks forward to the resource prospect of tight oil and gas, describes the geological characteristics of typical tight oil and gas reservoirs in China, and reveals the accumulation mechanism and enrichment regularity of tight oil and gas from the perspective of the Whole Petroleum System theory. The research results are as follows. (1) China’s tight oil and gas resources have broad prospects and great development potential, and great achievements have been made in the field of exploration and development, but there are still great challenges in the future, including geological theory, engineering technology and enhanced oil recovery technology. (2) Both physical property and accumulation process of tight oil and gas reservoir are between those of conventional oil-gas and shale oil-gas. The complex capillary network composed of pore throats within the tight reservoir is the key to the self-containment of tight oil and gas. (3) Oil and gas resources in different petroliferous basins in China show distinct differential enrichment characteristics. The Ordos Basin is a super tight oil and gas enrichment basin. (4) Based on the source-reservoir coupling relationship, tight oil and gas reservoirs can be classified into far-source type, near-source type, and intra-source type.