Abstract: Based on the necessity analysis of flexible capacity control in airline revenue management,a detailed account of the meaning, characteristics and the applications of these systems is given, which includes: overbooking system, callable system, aperiodic ticket system, opaque sales, probabilistic sales stand-by system, bumping strategy, last-minute discounts system, the replane concept, and so on. The current research work in these flexible capacity control systems is surveyed, and an overview and evaluation of current flexible capacity control models in revenue management is also provided, several directions for future research are proposed in the end.