In order to realize stray light suppressing for 4J32 alloy in fine optical system,the stray light suppressing coatings were prepared on 4J32 alloy from a conventional anodisation-plating bath containing Ce and dual salt additive.The bath formula and rational process parameters were investigated using a orthogonal test.By testing the influences of concentrations of K₂Cr₂O₇,MnSO₄and(NH₄)₂SO₄ in electrolyte solution,galvanic voltage,operating temperature and anodizing time on the anodizing films of 4J32 alloys,the optimal process conditions were gained as follows:20 g/L K₂Cr₂O₇,20 g/L MnSO₄,20 g/L(NH₄)₂SO₄,15 g/L Ce and dual salt additive,temperature of 25 ℃,last time of 20 min and voltage of 30 V.A black stray light suppressing film was obtained with the process.The results of reflection testing,thick testing and shock testing show that 4J32 stray light suppressing coating has a low-reflecting ratio(1.5%),a few dimension change(<0.8 μm) and good adhesion to substrate,and it is suitable to suppress the stray light in fine optic system.