Bipedal gait is one of the most important forms of human movement. However, every year many people lose their ability to walk due to disease. Weight support systems that reduce or even eliminate the effect of upper body mass loading on the lower limbs are among the most commonly used devices in gait rehabilitation. The designed weight support system provides body support while innovatively proposing a torso motion assist function. In this paper, walking experiments were performed on normal healthy subjects under five different weight-supported conditions, and motor and surface electromyography (sEMG) signals of the lower limb muscles were collected and analyzed. The results showed a slight decrease in joint motion of the lower extremities in the reference (free walking) and weight-supported-only assisted conditions, while there was no change in the joint angle curve waveform. In contrast, there was a significant change in the joint angle waveform between weight support plus trunk transfer and free walking. Different muscles differ in the significance of feature changes under different auxiliary conditions. By studying the changes in motor and muscle activation levels in the human lower extremity under the weight support system, it can be used as an indicator to assess specific gait indicators and muscle activity during the rehabilitation of the lower extremity in rehabilitated patients.