In order to explore the relationship between feeding quantity,water quality,and plankton in intensive grass carp farming ponds with salt-freshwater,the water quality,amount of feed,and plankton of three brackish water ponds in Guangzhou Chengyi Aquaculture Co.,Ltd. were sampled and investigated from September 2017 to September 2018. Spearman and Canoco 5.0 were then used to correlate and rank the data. The results showed that the feeding quantity was significantly positively correlated with the total nitrogen concentration of the water,with correlation coefficient of 0.614 (P<0.05),and was not correlated with the other water quality indicators including water temperature,pH,transparency,dissolved oxygen,nitrite,ammonia nitrogen,total phosphorus and salinity. The feed amount and phytoplankton biomass were significantly positively correlated,with the correlation coefficient of 0.354 (P<0.05),and the zooplankton biomass was extremely significantly positively correlated,with the correlation coefficient of 0.447 (P<0.01). The RDA ranking analysis was performed on the feed quantity,water quality index and plankton biomass. The sorting results showed that the feed quantity and total phosphorus were the key factors affecting zooplankton and phytoplankton biomass,respectively. The multiple regression data model fitted well,with the interpretation rate of the prediction model for phytoplankton and zooplankton biomass were 65.4% and 44.8%,respectively,and the models were Y1=16.07X4+13.60X3+11.10X2+2.22X6-2.20X5-2.06X1-51.57；Y2=2243.92x4+5.54x3+0.90x2+0.006x1－57.48 (Y1 is phytoplankton biomass,X1,X2,X3,X4,X5 and X6 are transparency,nitrite nitrogen,pH,total phosphorus,ammonia nitrogen,and dissolved oxygen,respectively; Y2 is zooplankton biomass,x1,x2,3 and x4 are feed amount,transparency,pH,salinity respectively). In conclusion,in intensive grass carp ponds with brackish water,the feeding quantity has a significant effect on the total nitrogen concentration and phytoplankton in the pond. At the same time,the purification ability of phytoplankton to the pond nitrogen also limits the amount of pond feed. Therefore,the regulation of the feeding quantity in the pond should take the water quality and plankton into consideration. It is suggested that when the phytoplankton biomass of this type of pond is 40-70 mg/L,the pond water environment is relatively good and stable.