Abstract: The application of TSI 3080 Electrostatic Classifier in sensitivity calibration for Dust Particle Counter is introduced. TSI 3080 Electrostatic Classifier can be used for extracting particles within a narrow range from the Particle Size Standards generated by an atomizer. The particle size distribution of the generated monodisperse aerosol in the corresponding size range measured by the Dust Particle Counter is 92%, the requirment of Methods of testing the performance of dust particle counter- calibration for sizing particle is 60%, the technique is a very useful tool to improve the measurement accuracy of the Dust Particle Counter.