In 1988,four clossed fish ponds (4-1,4-2,4-3,4-4) were selected to study the different types of main cultivated fingerlings in fish ponds in the saline-alkali wetland in Yucheng County of Shandong Province.In pond 4-1, 4-2, 4-3, 4-4, Oreochromis aureus, Hy pophthalmichtkys molilrix, Cyprinus corpio, Cienopharyngodon idellus are the main cultivated fishes, respectively.During 4-10 months, the abundance, biomass and the key environmental factors in the four fish ponds were tested.According to the changes in the major population of plankton, such as Protoza, Rotifera, Cyanophyta, Chlorophyta, Bacillariophyta, Cryptophyta and Euglenophyta, the steady and synchronous characteristics of the plankton in four different types of the fish ponds were analysed.In addition, the relationship between the environmental faotor, especially the nutritional factor, and the pleinkton were studied.As the growth and reproduction of plankton need an abundant nitrogen and phosphorus, there was a proportion suitable to N and P of about 15-30.1.During the cultivation period, the abundance of plankton had a positive interrelation with water temperature, but the water temperature reached an appropriate point, showing negative interrelation.The different proportions of the ferite feeding fish in ponds led to different species of plankton.In the pond of main cultivated Hypophthalmichthys moliltrix, the primary productivity is not on the decline.In favourable conditions, there would be more abundeince of plankton.