Abstract: Recently, due to excessive exploitation of marine resources, the ocean resources extremely decline. More and more serious marine pollution (especially inshore marine pollution) brings great difficulty for marine resources management. In order to better manage and utilize the marine resources, in this paper, we consider the effects of impulsive diffusion on the species in a polluted environment and investigate an inshoreoffshore fishery model. The sufficient conditions are obtained for the existence of the positive periodic solution and the global asymptotic stability of both the trivial periodic solution and the positive periodic solution. Moreover, in a polluted environment,the optimal harvesting policy is given for the inshore subpopulation, which includes the maximum sustainable yield and the corresponding harvesting effort. Numerical simulations confirm our theoretical results.