The migration of oil and gas is a crucial link between their generation and accumulation into reservoirs, reflecting the most significant characteristics of oil and gas as fluid mineral resources and is a key focus in petroleum geology. The migration process is complex and can be divided into primary migration and secondary migration based on its characteristics. These two types differ in terms of phase, driving forces, resistance, pathways, timing, and distance of oil and gas migration, which in turn affect the distribution of oil and gas within a basin. Therefore, understanding the content and methods of studying oil and gas migration is essential. This chapter mainly introduces the concepts of oil and gas migration, primary migration, secondary migration, research methods for oil and gas migration, and the relationship between the three fields (structural, fluid pressure, and thermal fields) and oil and gas migration.