Objective To simulate leg length discrepancy by unilateral increase in lower limb of normal person, analyze gait features in the case of leg length discrepancy and its effect on walking gait, so as to provide theoretical proofs for chronical musculoskeletal diseases in lower limb amputees due to leg length discrepency. Methods Leg length discrepancy was simulated by subjects wearing shoes to increase the unilateral height of one leg. The time-space parameters, ground reaction forces and joint angles of the subjects during normal walking gait and leg length discrepancy gait were obtained via the 3D motion capture system and the reaction force platform to make comparative analysis. Results Significant differences were found between leg length discrepancy gait and normal gait in terms of step length, stride time and single supporting period. In the case of leg length discrepancy gait, the ground reaction force of both feet significantly increased at heel-strike phase compared with normal gait, and obvious changes were observed in angles of hip, knee and ankle joints. Conclusions Leg length discrepancy is an important cause leading to gait abnormalities, and maybe a cause of leg joint diseases for trans-tibial amputees wearing prosthesis.