Abstract: The author has studied the fundamental composition and structure of sediments in intermediate and small sized red basins. On the basis of the study, the paper mainly discusses the problems in regional mapping and methods and contents of regional surveys. The author considers that alluvial fans in areas of red beds are a special type of sedimentary strata body. In order to reveal their temporal spatial distribution pattern, it is proposed that a basic mapping unit equivalent to the “formation” may be formed by various alluvial fans separated by some characteristic boundaries and generated by a synchronous diluvial event and that a fan may be further divided into lithological intervals and fan root, fan center and fan fringe faices zones.