Abstract: An micro-plot experiment was conducted to study the effect of rare earth on the bleeding composition of rice. The results showed that the vitality and synthesis of root and contents of amino acids and plant hormones, as well as contents of plant nutrients in bleeding sap of rice were greatly increased with lower concentration of rare earth, but inhibited by higher concentration of RE. The numerical simulation of data of three kinds of amino acids in bleeding sap reveals that the results fit well in with logarithmic equation and the 50 value (semi-effect value) calculated by this equation was about 350-500 mg/kg.