The impact of fine content of carbon black pellets on rubber mixing process and reasons for carbon black pellet degradation during pneumatic conveying process has been investigated and analyzed. The influential factors of carbon black degradation are introduced. It is identified and concluded that specific surface area of carbon black, size of carbon black pellets, parameters of pressure in conveying, conveying modes, materials of pipelines and conveying distance are major factors in the impact of degradation of carbon black. The conclusion is confirmed by the results of tests. The measures to reduce carbon black pellet fine content are proposed.