Abstract: In the paper, a Logistic model is studied for its application in fish harvesting. We impulsively put additional food (aquatic) into the lake to enlarge the carrying capacity. Thus, after a period of time, the amount of fish can reach a high level. We get the optimal strategy from the view point of ecology and economics. Our examples (Table 1-Table 10) give the detailed strategies. And the last examples (Table 11) compare the effects of different A and T. In the last, we interpret our mathematical and simulated results for ecological and economical application, and a brief discussion is presented.