It is emphasized by therapists that body-weight shifting to the corresponding leg during stance phase and moving to the other during swing phase is important to conduct efficient walking training and avoid loss of balance control. Kinematics and motion analysis are carried out on the pelvis area of healthy participants to obtain the lateral motion trajectory of pelvis in this paper. The significance of lateral shift during walking training is highlighted. The function of body-weight lateral shifting mechanism are proposed and designed to incorporate on the effective gait training based on Bio-engineering analysis. A prototype is designed to provide the lateral assistance for patients and shift the body weight as needed for a natural walking rehabilitation during human and machine interaction. The simulation results demonstrate the effectiveness of the proposed prototype and positively evaluated by doctors and therapists.