Mono-disperse PbFe12O19 nano-spheres were synthesized via a green hydrothermal method in the presence of lemon extract. Then star-like PbS and PbFe12-O19-PbS nanocomposites were synthesized by hydrothermal method. The prepared products were characterized by X-ray diffraction pattern, scanning electron microscopy, and Fourier transform infrared spectroscopy. Vibrating sample magnetometer illustrated that PbFe12O19 nanoparticles have either ferromagnetic or super-paramagnetic behaviour. The photo catalytic behaviour of PbFe12O19-PbS nanocomposites was evaluated using the degradation of three various azo dyes under ultraviolet light irradiation. The results show that nanocomposites have applicable magnetic and photo catalytic performance