摘要：In this paper, the problems of chaos and chaos control.for a class of susceptible-infected- removed （SIR） epidemic model with seasonal fluctuation are investigated. The season- ality in outbreak is natural among infectious diseases, as the common influenza, A type H1N1 influenza and so on. It is shown that there exist chaotic phenomena in the epidemic model. Furthermore, the tracking control.method is used to control.chaotic motions in the epidemic model. A feedback control.er is designed to achieve tracking of an ideal out- put. Thus, the density of infected individuals can converge to zero, in other words, thedisease can be disappeared. Finally, numerical simulations illustrate that the control.er is effective.