The different optical diagnostic techniques for determining dusty plasma parameters are presented. A comparative analysis of different methods for determining the gas-phase temperature and the density of alkali atoms in low-temperature thermal dusty plasma are carried out. The results obtained show that conventional gas-plasma diagnostics are inapplicable to dusty plasmas. Diagnostic methods allowing for the presence of dust grains are proposed and a system for determining the parameters of dusty plasma is developed. A combination of novel methods for determining the temperature, mean size, density and spectral refractive index of particles in high-temperature flows is described. The technique is based on empirical inversion of the forward-scattering transmittance and spectral emission-absorption measure ments. The measurements were successfully inverted for Al2O3, CeO2, and ash particles in plasma flows. The particle temperature, concentration, mean size, and complex refractive index are retrieved.