The reseaich on improving efficiency of PSB to plankton structure in low-lying saline-alkaline wetland ponds showed that PSB could enhance the number and the biomass of Cyanophya Cyptophyta Euglenophyta and Cryptophyta.Although Bacillariophyto dropped a little in general the small-type species increased.Moreover,PSB could enhance the number and the biomass of Cladocera and Rotifera especially those of the small-type Rotiferus.But those of Capepoda and Protozoa displayed a dropping tendency.Generally plankton displayed increases of numbers and decreases of biomass.Most species of plankton appeared certain increase,small-size geneses of plankton appeared more common than great-size ones which incrased the feed effect for fishes.In conclusion PSB could adjust and improve the structure of plankton community in saline-alkali wetland ponds.