Abstract: In pH 4.3 citric acid-disodium hydrogen phosphate buffer solution, bovine hemoglobin as a catalyst could accelerate the reaction rate of hydrogen peroxide oxidizing the excess KI to I3-, and I3- combined with basic dye ethyl violet to form ion association particles, which enhanced the resonance light scattering intensity greatly. Base on this, a new resonance scattering spectrometry was proposed for the determination of trace hydrogen peroxide in water samples. The increased resonance light scattering intensity (ΔI) at 659 nm was linear to the concentration of hydrogen peroxide in the range of 1.033×10-7-2.272×10-6mol·L-1, with the detection limit (3s/k) of 1.64×10-8mol·L-1. The method was applied to the determination of hydrogen peroxide in rain water samples, giving RSDs (n=5) less than 5.0% and recovery rates obtained by standard addition method in the range of 104%-105%.