In Ethiopia, the methods of co ee variety and standard identi cation is often throughrntraditional inspection and previous experience which is subjective and non e cient withrnthe basis of attributes of color, size, shape and rnavor, frequently examined by humanrninspectors. In this research, e cient and objective discrimination of co ee varieties andrnquality determination method is developed by investigating particle size dependency ofrnquality and rnavor of co ee using Laser light scattering technique. Particle size determi-rnnation for ve types of co ee samples (Unwashed Harar-4, Washed Lekempti-2, WashedrnSidamo-2, Washed Yirgache ee-2 and Washed Limu-2) were performed after determina-rntion of their optical properties with three phases of experiments. The results show that,rnall tested samples has high scattering coe cient in the forward direction as comparedrnto their negligible absorption coe cient. And their scattering coe cient has direct rela-rntion with their particle size as well as their quality and rnavor, the larger the scatteringrncoe cient is the nest the particle size and the highest the quality with good rnavor. Ac-rncordingly, Washed Yirgache ee-2 has highest scattering coe cient and nest particle sizernwith succession of others. In line with this, using liquid-liquid ca eine extraction methodrnthe participation of ca eine on scattering was tested for Unwashed Harar-4 Co ee sample.rnAnd the result show that, ca eine has its own comparable e ect on scattering. In generalrnthe obtained results were in excellent agreement with those obtained using traditionalrncup-test and other known methods. Thus, since the developed method have wider eco-rnnomic and scienti c applications, even for other turbid mediums, light scattering methodrnis the most preferable for classi cation of co ee quality standardsrnKey Words: Co ee, Standard, Airy Disk, Airy Pattern, Extraction, ScatteringrnOptical Properties, Particle Size