Abstract: A novel method combining centrifugation and backscattering technology was applied to analyze the stability of coal water slurry(CWS). The sedimentation behaviors of CWS prepared with a lean coal treated at different centrifu- gal speeds and centrifugal times were studied. The results indicate that the sedimentation of CWS in standing condition showed a significant delamination characteristic,while in centrifugal condition it mainly showed a system-compression characteristic with no significant delamination phenomenon. However,whether it was in static or centrifugal treatment, the core factors that lead to the CWS instability were particles coalescence and system subsidence. The particles coa- lescence dominated the evolution of CWS instability of the sedimentation area at the middle as well as the settling area at the bottom,while the system subsidence dominated the water liberation at the supernatant. It was found that the sta- bility index at the bottom 5 mm of the sample,whether in the static or centrifugal condition,could be used to identify the occurrence time and the evolution period of the soft deposition,and the time when the hard settling began to gener- ate. This finding provided a valuable reference for the rapid,quantitative and accurate characterization of coal water slurry stability.