On the basis of the theory of continuous compaction technology, we put forward the vibratory compaction value (VCV) index measured by a roller compactor, in order to evaluate the quality of continuously compacted subgrade.The relationships between the VCV index and the currently used indexes K30, Evd, Evl and Ev2, were explored by analyzing the experimental data collected from two test sections on the Beijing - Shanghai High-Speed Railway.The result shows that the VCV index has a linear relationship with the currently used indexes.