Objective To collect the kinematics and kinetics functional parameters of healthy human lower limbs during stair ascent and descent, so as to provide data for designing the gait trajectory and selecting the driving components of the exoskeleton walker to achieve the motion of stair climbing. Methods Common staircase as an experimental setup was designed, and the three-dimensional (3D) motion capture system and 3D force plate were used to simultaneously measure the ankle, knee, hip motion information during stair ascent and descent. The movement characteristics of the lower limb during stair climbing was analyzed by SPSS statistical software and Origin graphics software, and the functional parameters during stair ascent and decent were also compared and analyzed. Results The joint angle at the sagittal plane, joint moment variation with gait and activity limits in lower limbs of healthy youth during stair ascent and descent were obtained by the experiment. The ranges of motion in ankle，knee and hip joints during stair ascent were -10.66°-13.26°, 6.85°-88.92°, 1.31°-50.18°,while those during stair descent were -37.42°-27.18°,9.83°-95.53°,8.01°-31.62°.The maximum ankle, knee and hip joint moment during stair ascent and descent were 1.788, 1.121, 0.946 N?m/kg, respectively. Conclusions The gait parameters variation with gait and the joint range of motion in human lower limb were significantly different during stair ascent and descent. Separate design targeting at stair ascent or stair descent is required for gait planning of walking aids, and the selection of driving element should consider the maximum moment in each joint during stair ascent and descent.