The invention relates to a preparation method and application of an iron-sulfur heterogeneous Fenton-like catalyst. The preparation method comprises the following steps of adding a dispersing agent into a ferrous solution, and performing uniform stirring; sequentially and slowly pouring solutions of hydrosulfide and sulfide into the solution, keeping the pH of the solution to be 5.0 to 5.5, and performing stirring for 10 to 20min; slowly adding a solution of sulfite into the solution, keeping the pH value to be 5.0 to 5.5, and performing stirring for 5 to 10min to obtain precursor sol; transferring the precursor sol into a sealed glass bottle, and performing constant temperature (25 DEG C) aging reaction in dark to obtain black precipitates, i.e. the final catalyst. The pH of wastewater is regulated to 7.0 to 11.0, a mixed solution of hydrogen peroxide / persulfate and the synthesized heterogeneous fenton-like catalyst are added into the wastewater, and stirring reaction is performed for 10 to 120min to finish the degrading of organic pollutants in the wastewater. A preparation process of the prepared iron-sulfur heterogeneous Fenton-like catalyst is simple, conditions are mild, and when being used, the prepared iron-sulfur heterogeneous Fenton-like catalyst is large in applicable pH range, and has a good deep treatment effect on industrial wastewater.