The invention provides a particle size analysis method for carbon black in acrylic rubber, which is characterized by comprising steps: (1) smashing acrylic rubber and adding a photocatalyst; (2) performing light irradiation treatment on the acrylic rubber obtained in step (1); (3) mixing the product obtained in step (2) with an alkali solution; (4) mixing the residual solid A in the solution in step (3) with an acid solution; (5) placing residual solid in the step (4) into a solvent for supersonic dispersing; (6) detecting the particle size of the carbon black in step (5). The detection method has the characteristics of accuracy and high operability.