Abstract: In this paper, the concept of effective source rocks refers to those of source rocks in which the hydrocarbons already generated have been expelled or diffused out from their mature source rocks. Not only the meth-ods and procedures are introduced in detail to distinguish the effective source rocks from ineffective ones,but also the various geological factors influencing the development and distribution of effective source rocks are discussed,and the relationship between the effective source rocks and oil/gas pools are studied as well. It is pointed out that only the effective source rocks are the real source of oil and gas.