The suspended particle size distribution provides crucial information for the study of water environment structure and function. Based on the in-situ data from wet and dry season in 2008—2011, the paper studied suspended particle size distribution of Poyang Lake and its optical features. The suspended particle size distribution showed seasonal variation: the particle size of southern lake was larger than that of northern lake in dry season but showed little variation in wet season. The suspended particle size distribution exerted influence on particulate absorption coefficient, attenuation coefficient and scattering coefficient. The particulate absorption coefficient of northern lake was higher than that of southern lake. The negative correlation between specific absorption coefficient of total suspended particles and median particle size indicated that there was “package effect” of mineral particles in turbid Poyang Lake. The spatial and temporal distribution of particulate attenuation coefficient and scattering coefficient are similar: there were obvious regional differences in dry season but few in wet season. There were good correlations among the remote sensing reflectance, spectra slope of particle size distribution and spectra slope of particulate scattering coefficient. These correlations would provide the foundation for remote sensing retrieval of particle size and quantitative analysis of influence of suspended particle size on the optical properties. The relationship between particle size distribution, particulate backscattering coefficient and bulk refractive index can provide information of particle composition in Poyang Lake.