Carbon nanofibers(CNFs) were in situ grown on the surface of carbon/carbon composites with different density by chemical vapor deposition(CVD). In order to seek the optimal process, the influences of different parameters on the CNFs microstructure were investigated and discussed. Using the C/C composites modified by in-situ grown CNFs and pure C/C composites as the research objects, the growth mechanism of in-situ grown CNFs was described and the graphitization degree,the mechanical properties and thermal c...