A visible light catalyst, its preparation method, a visible light catalyst activated persulfate system and its use. The visible light catalyst includes a carbon material, a transition metal compound and a coating material. The carbon material is conductive carbon material, and the transition metal compound is selected from one or more of transition metal oxides, transition metal sulfides, and acid or salt compounds containing a transition metal. The visible light catalyst has high visible light photocatalytic activity and performance of degrading organic pollutants and activating persulfate which can result in synergistically degrading degradation-resistant organic pollutants.