Mixed principles and me thods with differen t basic water for re ar ing larva of Chinese mit ten cr ab (Eriocheir sinensis)were studied from 1995 to 1996 on the Ping Hu Fisheries Test Farm of Zhej iang Pr ovince .The results were as fol lows : Using freshwater as the basic water in the fish pond for rear ing lar va , six chemical reagents(MgSO4 ,CaCl2 ,KCl , FeCl3 ,H3BO3 , NaCl)must be added to the basic water .Using deep-well water as the basic water the above 6 chemical reagents and KBr , KI ,Na2H2PO4 , CuSO4 must be added to the basic water .The suitable contents of Mg2+ and Ca2 in both the mixed water wer e 484 ～ 816mg/L and 178 ～ 340mg/ L r espect ively at Mg2 /Ca2 (R)of 2 .0 ～ 3 .0 .The study showed rear ing larva with alongshor e estuar y water was the most economical way .I f the contents of Mg2 ,Ca2 or R were not in the above suitable r anges , the basic water could be diluted with freshwater , or concentr ated se awa ter could be added to the basic wate r , then the contents of Mg2 , Ca2 or R could be mixed to the above suitable ranges .