Abstract: It is devoted to study a class of optimal harvesting problem for a non-autonomous Gilpin-Ayala model with impulsive harvests,and the species is harvested at fixed moments.By choosing the harvesting efforts as control variables,we study a maximum harvesting problem in given time range for a general non-autonomous Gilpin-Ayala system.Firstly,we obtain the singular harvesting strategy by using the maximum principle of impulsive differential system.Furthermore,we consider the control problems for the situations in which the singular controls are blocked at some harvesting moments.Therefore we first establish an optimization principle:the optimal path lies as close as possible to the singular path.And based on this optimization principle,the optimal harvest strategies in some blocked situations are obtained.The results of this paper extend and improved some relevant conclusions about the control problem with impulsive harvests.