The invention discloses an antifouling coating for a surface of a direct current field device, and a preparation method and an application thereof. The coating is nano titanium dioxide containing molybdenum disulfide and a chrome matter; the preparation method includes the following steps: 1) weighing a chromium nitrate solution and a 1-100 mol/L NaOH solution, and mixing evenly; 2) adding titanium dioxide P25 into the mixed solution prepared in the step 1), wherein the molar ratio of chromium to titanium is (0.1-10):100; 3) adding MoS2 into the mixed solution prepared in the step 2); 4) placing the mixed system prepared in the step 3) in a drying oven; and 5) washing the sample prepared in the step 4) with water to neutral, carrying out acid stirring, carrying out water washing and drying. The coating provided by the invention coats on the surface of the direct current field device, and can effectively slow down and prevent filth deposition.