CdTe quantum dots(QDs) modified with —COOH on its′surface were synthesized by using mercaptoacetic acid hydrothermal synthesis，and QDs were connected to the Fe3O4 nanoparticles to prepare CdTe/Fe3O4 magnetic quantum dots.The magnetic quantum dots could be modified on the graphite electrode surface by magnetic force.In pH 7.5 PBS buffer solution，ECL of CdTe quantum dots can be generated by promotion of H2O2.There was a good linear relationship between ECL intensity and H2O2 concentration in the range of 4-100 μmol/L with a detection limit of 0.24 μmol/L.Based on this，an ECL method for the determination of hydrogen peroxide was established.The method was successfully applied in the determination of hydrogen peroxide concentration in Leersia hexandra Swartz extracting juice.With the aid of nano-Fe3O4 magnetic particles，the sensor could easily form and renewal the sensitive membrane by magnetic controlling.The experimental operation was simplified and the ECL intensity was improved significantly.