Since the implementation of the national coal resource potential evaluation, the determination of the basic evaluation unit is a primary problem to be solved. According to the characteristics of coal resource distribution, the basic unit of coal resource potential evaluation was identified into three basic types, namely, the main unit of development, the main unit of exploration, and the main unit of prediction, and the basic evaluation unit was defined as prospect area, coal production area, and mining area; the principles for determining the three types of evaluation units were discussed.