Objective To compare biomechanical characteristics of the knee joint during forward walking and backward walking. Methods Temporal-spatial, kinematics, kinetics parameters of 13 healthy young male volunteers were collected and compared by 3D motion capture system Vicon T40 and force platforms AMTI OR6-7. Results Compared with forward walking, the speed, cadence and stride length significantly decreased, while the gait cycle and stance phase percentage in gait cycle significantly increased during backward walking. In the sagittal plane, the range of motion (ROM), the maximum flexion/extension moment of the knee were smaller during backward walking. In the frontal plane, the ROM of knee varus/valgus during backward walking decreased, and the peak value of knee adduction moment significantly reduced in the early stance phase while significantly increased in the late stance phase of backward walking. The peak value of ground reaction force (GRF) was significantly larger in the early stance phase while smaller in the late stance phase during backward walking than that during forward walking. Conclusions The biomechanical characteristics of the knee joint during forward walking and backward walking are significantly different. Compared with forward walking, backward walking is helpful to reduce the medial compartment load in the early stance phase. Further study will be needed to investigate the effects of backward walking on knee joint loading in the late stance phase.