Abstract: Using independently developed microcosmic structure analysis system of nanocomposites which is based on the image processing technology, this paper carried on quantitative analysis of microcosmic structure of SiC/PTFE nanocomposite by computational method of particle dispersion degree. The results indicate that: The particle dispersion degree can take a good quantitative attribute of uniformity of nanoparticles which disperse in the PTFE matrix; Along with the content of SiC nanoparticle increases, the particle dispersion degree increases first and then decreases; When the content of SiC nanoparticle is 7%, the particle dispersion degree is quite large, and the nanoparticles disperse quite uniformly in the composite; The treatment by coupling agent may enhance the particle dispersion degree of SiC nanoparticles in PTFE matrix.