An analytical method was developed to calculate efficiency of densifying carbon/carbon (C/C) composite with pitch for each cycle. Three factors were defined in the densificationprocess: an impregnation efficiency, w, a retention efficiency, x, and an overall densification efficiency, E. The relationships developed were applied to the results for three cycles of densification of C/C composite to evaluate the factors which depend on the route of impregnation and carbonization. The impregnation efficiency increases as the process is repeated due to a decrease of porosity, and the retention efficiency shows a tendency to be in a reverse proportion to the impregnation efficiency. The overall densification efficiency depends on the carbonization yield of pitch impregnant. The carbonization route P+A+G is the most effective method in densifying C/C composites, in which pressure carbonization(P) increases the carbonization yield and the retention efficiency of pitch, and graphitization(G) increases the impregnation efficiency.