Abstract: Using the specified triaxial loading equipment corresponding to the CT machine, the comparison of real-time computerized tomography testing of damage failure mechanism of cracked rock in cold region under successive triaxial loading and unloading has been accomplished .The evolution law of CT number and CT images in the complete process of damage failure of frozen cracked rock is studied. It shows that it is easy for failure phenomenon to happen suddenly in the process of unloading of frozen cracked rock compared to the successive triaxial loading .The size of volume expansion of frozen cracked rock in unloading condition is larger than that in successive loading condition.