The as-synthesized BiOCl nanoparticles were characterized by x-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) techniques. The XRD pattern showed that a highly pure and crystalline phase has been obtained. The UV-vis diffuse reflectance spectroscopy (DRS) studies revealed the indirect band gap value of about 3.32eV for the fabricated semiconductor. The disappearance of the dye, monitored spectrophotometrically, follows approximately pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Besides, the effect of some parameters such as the influence of the initial pH, catalyst weight, initial dye concentration, oxidant concentration, and salt concentration on the degradation of malachite green dye solution under visible light irradiation were investigated. The optimum conditions for the degradation of dye were 25mgL(-1) dye concentration, pH of 8, and a catalyst amount of 0.7gmL(-1). The addition of an optimal amount of hydrogen peroxide and potassium persulfate increases the degradation rate while NaCl and Na2CO3 decrease the rate. Complete mineralization has been confirmed by UV-Vis spectroscopy