Abstarct: Abstract Direct blue dye (DB), which is used in the textile industry, is a group of azo dyes. This dye has a high resistance to light, temperature and washing, therefore, removing this dye from textile industry effluent is a difficult task. In this research, biochar magnetized nanocomposite was used to degrade DB dye from solution and its photocatalytic degradation percentage was calculated. For this purpose, biochar synthesis of pomegranate peel was done first, and to magnetize it, biochar synthesis was done with Fe3O4. The structure of this compound was characterized and confirmed using techniques such as scanning electron microscopy FESEM, XRD, VSM and EDAX analysis. Parameters such as solution pH, photocatalyst amount, temperature, duration and initial solution concentration were evaluated during the reaction. According to the obtained results, the 0.0075 amount of magnetized biochar in optimal conditions with a concentration of 50 ppm at pH = 5, at the temperature of the laboratory environment (25°C) at 30 minutes showed its optimal performance in the degradation of DB dye. Kinetic analysis showed that it follows the pseudo-second order model. To check the stability of the photocatalyst and its recyclability, the synthesized compound was reused four times under optimal conditions, which showed a good degradation percentage, which indicates its recyclability