Abstract: Stress uniformity along the axial direction in specimens of split Hopkinson pressure bar (SHPB) tests was investigated. By theory of one-dimensional elastic stress wave, the temporal and spatial distribution of stress in specimen induced by incident pulses with any rising shape was derived. Wave propagation processes in specimens were calculated under rectangular, trapezoidal and sloping waves, which were uniquely expressed as the trapezoidal type by the parameter of rise time. Stress uniformity histories were obtained, and the influences of relative rise time of incident pulse and specimen-bar relative mechanical impedance on relative time required for stress uniformity were investigated. Researched results can provide guidelines to design and analyze SHPB tests.