Abstract: The oil and gas resource abundance is one of the key parameters in resource assessment, and the determination of this parameter is of great significance. The statistical analysis of the abundance of oil and natural gas resources in key basins in China is conducted, which indicates that the conventional oil and gas resources in the major proliferous basins is dominated by medium-low abundance. The resource abundance in most blocks is ultra-low to low, and it is high in only a few dominant blocks. On this basis, the geological factors affecting the abundance of oil and gas resources are determined, including three main controlling factors of hydrocarbon generation intensity, trap area coefficient, and regional unconformities. By using the three main controlling factors, prediction model of conventional oil and gas resource amount is established for foreland basin, cratonic basin and rift basin. Subsequently, the model is applied to six sags in the three types of basins, and relatively consistent results of the calculated resource amount are obtained with those in the fourth round oil and gas resource assessment, indicating advantages of simple operation, reliable results and easy application of this prediction method, which can be used to preliminarily predict the amount of conventional oil and gas resources in areas with less abundant data and low degree of exploration.