Army aviation Rotary-Wing (RW) aircrafts can implement Air-to-Ground Operation (AGO) support to ground troops as well as the traditional Close Air Support (CAS).At present,studies on the CAS of Fixed-Wing (FW) aircrafts have been carried out by some domestic researchers,but there are few reports on the relationship between the AGO Attacks Against Enemy Forces in Close Friendly Contact (AGO-AAEFCFC) and CAS.Aiming at the problems,and by taking the American army as the object of study,we make study on the basis of a series of USF Field Manuals and joint publications.Firstly,the AGO-AAEFCFC and traditional CAS operational models are reviewed and analyzed.Then,the relationship and difference between the AGO-AAEFCFC and CAS in aspects of combat purpose,application mode and concrete implementation are presented.