Abstract: In the industry of civil aviation，delay propagation of flight always is a main factor that impacts the flight’s delay.This paper discusses the delay propagation problem in busy hub-airport.All the data used in the experiments is come from real records of one large domestic airlines.Through producing the model of delay propagation and modeling the Bayesian Net，the impact of arrival-delay on departure-delay between related flights is discussed.The outcomes of learned Bayesian net show that the existence of propagation phenomenon from arrival-delay impacts onto departure-delay；the degrees under varied circumstance are different；and the according coping methods are different.Cancellation of flights is a drastic remedy of those coping methods.It can weaken the delay propagation to some extent.The weakened degree is related to the number of flights cancelled.A preliminary reference can be made based on this research for airports when there is large scale delays of flights happened.