This paper embodies the results of hydrochemical survey and tha estimations of phytoplanktoz production in eight high-yield fish ponds of Helie commume Wuxi from May to August 19TT. Three ponds of Wuxi Hu fish farm are also studied for comparison. The high-yield ponds have moderate main ions in content, with a ovnstant pH value The effective nitrogen of the water averaged 1.24mg jI, among which NH₄---N 61%，11TDa N i8 o and NO₂-N 24%. The soluble reactive phosphorus is 0.028 mg/L. COD_mn is 13.3mg/L. Owing to the high N/P value (61--139)，the phosphorus should be the limiting factor of the promary productivity.