Abstract: The behavior of quasi-brittle materials like cement mortar depends on the level of confinement. In order to study the dynamic behavior of cement mortar under active confinement, An device which fits the split Hopkinson bar loading was developed, and it provides the lateral confining pressure upper to 30 MPa. The axial stress-strain curves under various level of confinement and strain rate were derived according to the experiment. It shows that the strength and ductility increase significantly because of confinement, and finally turn into plasticity, also it is strain rate sensitive.