In present work, study of dielectric and fluorescence properties of polystyrene (PS)- chromium oxide (Cr2O3) and polystyrene- chromium oxide doped by zinc cobalt iron oxides nanocomposites have been investigated. The samples have been prepared by adding ZnCoFe2O4 nanoparticles concentrations to the (PS-Cr2O3) nanocomposites by different weight percentages are (0, 2,4,6 and 8) wt.%. The results showed that the dielectric constant, dielectric loss and A.C electrical conductivity of (PS-Cr2O3) nanocomposites increase with an increase in ZnCoFe2O4 nanoparticles concentrations. The dielectric constant and dielectric loss decrease while the electrical conductivity increases with an increase in frequency. The results of dielectric and fluorescence properties showed that the (PS-Cr2O3/ZnCoFe2O4) nanocomposites can be used in different optoelectronics applications.