The real time scanning observation on meso damage process in concrete was carried out using CT technology. CT images of crack propagation，coalescence and failure were obtained under static and dynamic tension. Meso-damage mechanism of concrete under tension was analyzed the mean CT numbers in large statistical region small statistic region of scanning layers ROI.The results showed that the cracks developed in the interface of weak region and expanded to adjacent weak partsthe mean CT numbers of the two statistical regions showed decreasing trend. Parts of aggregates were ruptured when the concrete was damaged under static tension. While in small statistic region，the cracks developed in the interface of weak region and expanded along the fastest path，and the mean CT numbers showed a decreasing trend The mean CT numbers in large statistical region changed slightly. The aggregate divorced from mortar along interface，and the failure plane was smoother when the concrete was damaged under dynamic tension. So，the aggregate was ruptured obviously because the loading rate was higher.