Abstract: In recent years, major oil and gas discoveries have continuously been made in South America. Relevant research works are conducted on the basis of previous geological studies to understand the spatial distribution and the amount of undiscovered oil and gas resources in South America, so as to provided reference for the selection of strategic exploration area. Controlled by the regional tectonism such as subduction of the Pacific Plate and pull apart of the South Atlantic, the South American continent has different tectonic evolution characteristics of its eastern, western, southern and northern structural parts, developing various types of sedimentary basins such as craton,fore-arc, back-arc, foreland and passive continental margin. The statistical analysis of the distribution of discovered oil and gas fields in various countries, basins and reservoir formation shows that the oil and gas resources are widely distributed in South America with various degrees of enrichment. Most of the oil and gas reserves are concentrated few countries. The oil and gas resources are the most abundant in two types of basins, i.e., the foreland basins of collision continental margin in the western South America and the passive continental margin basins on the eastern Atlantic coast, with the main reservoir of the Mesozoic sandstone and carbonate rocks. The trap evaluation method and analogy method are applied to estimate the undiscovered resources in 56 petroliferous basins with different exploration levels. The results show that it still has great potential for oil and gas exploration in South America, with the undiscovered recoverable oil and gas resources of 50.35 billion tons of oil equivalent. The future exploration will focus not only on basins with high exploration level, but also on those with low exploration level.