Abstract: This study conducts rolling compaction tests of earth-rock dam material and examines roller vibration behaviors ? acceleration in time and frequency domains, and obtains the law of the amplitude and distortion degree of the roller acceleration varying with compaction degree and roller vibration frequency. On this basis, we find the disadvantages of the existing indexes for characterizing compaction quality, including ground reaction force index (Fs) and compaction value (CV) which are based on acceleration time and frequency domain analysis respectively. An improved ground reaction force index for consideration of lag phase angle and a compaction monitor index for the combined effect of roller vibration frequency and acceleration harmonics are then put forward in this paper. Application in case studies shows that these two improved indexes for compaction monitoring are better in correlation with rolling passes and material compactness, helping reduce the errors in characterization of the compactness of earth-rock dam materials. Thus the improved indexes would provide a new way of real-time monitoring on earth-rock dam construction quality.