Abstract：By constructing the equivalent system and Lyapunov function, the stability for a kind of third order impulsive differential system at fixed times is investigated. Stability is obtained for a kind of impulsive differential system at fixed times by themethods involving construction of Lyapunov function. So the conclusion is drawn that p （t） = 1 is the full condition of uniform stability for a generic impulsive differential system at fixed times. The impulsive effect on the stability of the system of crucial impact is also studied. Finally the application of this method is illustrated with some examples.
2009, Vol. 30 
