Abstract: The photovoltaic industry in China is large, the treatment of fluorine-containing wastewater will generate a lot of by-products, fluorine-containing sludge, of which calcium fluoride accounts for more than 40%. It is noted that fluorine-containing sludge can replace natural fluorite ore after purification, and this will bring high market value. Accordingto the analysis of physical and chemical properties, fluoride-containing sludge not only has corrosive, toxic and other hazardous characteristics, but also has the difficulty of disposal and low utilization. Therefore, it was proposed to optimize washing pickling method by wastewater reuse and purification, so as to achieve the wastewater treatment and reduce the high cost of hydrofluoric acid inputs, while enriching F ^- and utilizing the newly generated Cl ^- containing wastewater and F ^- containing wastewater. By controlling the dosage of HCl, pH, reaction time, temperature and stirring rate, and comprehensively considering the operability and economic benefits of industrial production, the purity of calcium fluoride sludge can reach more than 90%.