The invention relates to a method for treating and recycling calcium sulfate by the aid of ferrophosphorus which is used as a reducing agent. The method includes calcining calcium sulfate mixtures and the ferrophosphorus used as the reducing agent in CO2 atmosphere to generate SO2 gas capable of being used in follow-up procedures and products such as iron oxide and phosphate. The method has the advantages that sulfur elements in the calcium sulfate can be recycled in the mode, and accordingly the novel method can be provided for recycling the calcium sulfate; the ferrophosphorus can come from ferrophosphorus slag which is a chemical byproduct, and accordingly the method is low in cost; the sulfur elements are recycled, and the ferrophosphorus which is difficult to use is converted into the phosphate or pyrophosphate and can be conveniently added into phosphoric acid industries in follow-up working procedures to be recycled; the method includes simple processes, has low requirements on process equipment, is low in energy consumption and applicable to comprehensive utilization of calcium phosphate and the ferrophosphorus and scale industrial low-cost clean production and has a high benefit, and reaction is easy to implement.