Abstract: In this paper, PP/CB films with 2.2wt% carbon black(CB) content and 3.3wt% CB content were prepared via Melt Blending-Masterbatch Dilution Method, assisted by high-efficiency dynamic mixer. A potential on-line measurement new method, color difference, was taken to characterize the dispersion CB particles in polypropylene matrix. The standard color difference of films is less than 1.5NBS, while the color difference between every two samples is less than 1NBS. The color difference between every two samples reflects actual difference between than standard color difference, and it can also exclude abnormal samples. The color difference of films with 3.3wt% CB content is less than that of films with 2.2wt% CB content. Too high CB content masks the dispersion of CB on color difference. The testing method of skewness-kurtosis was employed to test normal distribution of color difference values and its significance. It shows that color difference values approximately follow normal distribution. Given significance level α=0.05, the mean value of color difference is less than 1NBS and there is no significant difference between films, which indicates that CB particles achieve the desired dispersion state in polymeric matrix. The color difference values and gray series exist the following relationship: when CD≤3.4, GS=5-CD/1.7；when CD＞3.4, GS=5-lg(CD/0.85)/lg2. After calculating, the mean color difference of films is 0.54NBS and the gray series is 4.68, which shows no color difference between films and a good mixing state between CB particles and polymeric matrix.