Abstract: The paper aimed to reduce nitrate accumulation of pakchoi under solution culture by regulating nutrient during the short period just before harvest. The regulating methods are as follows: reducing N content in nutrient, replacing NO3- with NH4+; eliminating N completely from Nutrient; and using Cl- and SO42- as osmoregulation substituting NO3-. All these resulted in lower nitrate content in pakchoi, the experiment also showed adding Cl- and SO42- basing on reducing N amount had better effect on reducing nitrate accumulation of pakchoi, the effect of Cl- was better than SO42-. However, the treatments of eliminating N completely and adding organic acid salt reduced nitrate content significantly and also decreased pakchoi yield.