Abstract: We studied the effects of different amount biostimulants supplement on the removal efficiency of nitrogen, phosphorus and COD in vertical flow constructed wetland. The mechanism was analyzed by determining the activities of substrate phosphatase and urease in the constructed wetland systems. The results showed that biostimulanta suppklement could improve nitrogen removal efficiency in the systems, and the removal rates of \rmNH_4^ + -N and TN reached up to 80%, increasing by 71.5% and 31.7% respectively when compared with the control group. The maximum removal rates of TP and COD reached up to 36.0% and 91.6%, increasing by 9.1% and 5.9%, respectively. Meanwhile, the biostimulants could improve the enzymatic activities of substrate phosphatase and urease in the system, and the biostimulants had a significant influence on substrate urease activity. Significant positive relationships were found between COD removal rate and the activities of substrate phosphatase and urease. The most suitable amount of biostimulant supplement used in this system is 5 μL/L, which means 5 μL biostimulants was supplied to 1 L influent.