Abstract: This paper mainly introduced the general situation and principal geological features of several typical “Small and fat”basins both at home and abroad, including the Los Angels basin in California of U.S.A.,the Miyang basin in Henan province of Eastern China and the Jiuxi basin in Hexi corridor of Western China. Principal factors controlling the hydrocarbons enrichment and distribution were analyzed. Finally, a summary was made on the experiences and lessons in oil-gas exploration achieved medium-small basins, it is considered that these understandings can be used as important reference in oil and gas exploration of western China 's medium-small basins.

Key words: medium type, small type, petroliferous basin, geologic characteristics, oil and gas distribution, oil and gas exploration