According to the tectonic evolution,structure of section,sequence relationship and source-reservoir-cap composition of foreland basins,the foreland basins can be divided into two types including epicontinental foreland basin and intracontinental foreland basin.

There are three kinds of fore-land basins classified in terms of origin and location:peripheral foreland basin,retroarc foreland basin and regenerated foreland basin.

Along with Tajik Basin and the Southwest Southwest Depression of Tarim Basin, Alay Basin was one of the remnant basins on the north rim of the Tethys during the Late Triassic to Paleogene, it became a peripheral foreland basin in Miocene.

Dickinson formally introduced the term foreland basin and proposed two geneticclasses:(1)peripheral foreland basin and (2)retro- arc foreland basin.

Transporting conditions of faults required in formation of large and medium gas fields with high efficiency in foreland basin;

Different origins of natural gas in secondary gas pool in Western Sichuan foreland basin;

Overpressure compartment sealed by faults in Kuqa foreland basin;

Based on forland basins evolution,tectonic features,sedimental model,thermal process,reform process and model recovery,the paper analyzes forland basins theories and pays more attention to geological process,evolutional development and sedimental model.