Abstract: The mechanical properties and transformation behavior of NiTi shape memory alloy under constant strain constraint with and without vibration were investigated by using tensile test machine, CSM002 type material test equipment and differential scanning calorimeter (DSC). With increasing the amplitude of vibration, the two-stage recovery strain of NiTi alloy obtained during free heating decreased. With increasing the time of vibration, the recovery stress of NiTi alloy generated under constraint also decreased. The DSC results showed that the second reverse transformation peak temperature of NiTi alloy after vibration under constraint increased slightly during the subsequent heating. The transformation heat of the two reverse transformation peaks had an opposite change, the first one increased, while the second one decreased. All these results indicated that the recovery stress of NiTi alloy generated under constant constraint decreased due to vibration. These could be caused by microscopic plastic deformation during vibration.