Abstract: The treatment of spraying cerium trichloride and rare earth nitrate on sugarcane with three concentrations (100, 300, 600 mg/L ) were done at middle tillering stage. The isozyme of peroxidase and esterase of leaf was assayed by means of polyacrylamide gel electrophoresis at the 3th day for the treatment of cerium trichloride and at the 20th day for the treatment of rare earth nitrate. The results showed that both types of rare earth had influences on foe isozyme level, but were different from each other. In the treatments of three concentrations, it was found that the effect of 300 mg/L was most distinct with more enzyme bands coloured deeply, 100mg/L secondly and 600 mg/L indistinct. On zymograms of esterase isozyme and peroxidase isozyme treated with cerium trichloride , the enzyme bands were increased or decreased in some zones.