In order to study the optical properties of different modes of marine atmospheric aerosols, coarse and fine modal classification and complex refractive index inversions are carried out and studied based on the Mie scattering theory of spherical particles. This is done using tools such as a visibility meter, automatic weather station, optical particle counter (OPC), and cavity attenuated phase shift (CAPS) single scattering albedo monitor. The inversions are carried out for atmospheric aerosols in the coastal waters of Maoming, Guangdong. The results show that the refractive index of fine-modal aerosol at 530 nm is approximately 1.35 (±0.01)?0.019 (±0.003)i when the relative humidity is greater than 55%, and it is 1.37 (±0.02)?0.020 (±0.003)i when the relative humidity is less than 55%. The refractive index of coarse-modal aerosol is approximately 1.40?0.002 (±0.002)i when the relative humidity is greater than 55%, and it is 1.48 (±0.02)?0.005(±0.002)i when the relative humidity is less than 55%. There is a clear difference in the refractive indexes of aerosol particles in different modals, which has a reference value for studies of the marine aerosol climate effect and the establishment of aerosol models in the Maoming sea area.