A new Optical Particle Counter(OPC) with 60° and 110° double-scattering angles was developed in the paper for measuring aerosol refractive indexes and size distributions synchronously.On the basis of defining a sensitive function by Mie scattering theory,two optimum scattering angles were selected,then,the difference of two sattering angles sensitive to aerosol refractive indexes was used to inverse the aerosol refractive indexes.Finally,a prototype with 60° and 110° double scattering-angle of OPC (D-OPC) was used in the experiments at Hefei for measuring aerosol refractive indexes and size distributions.The scattering and absorption coefficient values measured by the D-OPC were compared with that measured by an Aethalometre and an Integrating Nephelometer(designed by TSI).The comparison results indicate that measured data by the D-OPC are reasonable and the measuring error is less than 20%,which shows the D-OPC can satisfy the requirements of measurement of aerosol refractive indexes and size distributions synchronougly.