Concrete material under the dynamic load has different characteristics with itself under the static load. This paper study on the CT test，the plain concrete specimen under dynamic loading as the object of study. Analysis the concrete meso structure change effect on the dynamic mechanical properties such as strength, deformation and damage morphology under the sine wave dynamic pressure and dynamic tensile load. Through the research of CT difference image, the moving crack in concrete compressive loads is developed rapidly, short failure process, failure crack is much, damage area is large, etc; Through CT number density segmentation image research, the dynamic tensile loading concrete micro crack suddenly merged to form a main crack through the specimen, the specimen breaks suddenly. By research the CT number change law in the process of loading, the concrete density decrease after a first increases under the dynamic pressure load, specimens experienced compaction, expansion, crack coalescence until finally the failure process, and the specimen under the dynamic tensile load density continuously reduced until fracture, early without load compaction. Different stress state of concrete under dynamic pressure, dynamic, lead to the damage degree is different, the formation of the crack area is different, the total energy required is different also, eventually led to the determination of the strength of the different, different stress state is the root cause of the dynamic pressure, the difference of dynamic tensile strength.