Objective By establishing the intervention mode of 12-week gait retraining (GR) (with the specific aim of changing the habitual running gait), to determine the changes of vertical ground reaction force (vGRF), kinematics and dynamics of hip, knee, ankle joints, as well as stiffness of lower limbs in running before and after GR, and to explore the influence of running posture transformation on impact force and lower limb biomechanics. Methods Vicon motion capture system and Kistler 3D force measurement platform were used to collect the GRF and marker track of 30 runners (15 in experimental group and 15 in control group) before and after GR with the minimalist shoes at a speed of 12 km/h±5%. Results A total of 17 subjects (9 in experimental group and 8 in control group) completed the GR. After GR, the maximum loading rate of both groups decreased significantly, and the maximum loading rate of experimental group was lower than that of control group. The foot strike angle in experimental group decreased significantly after GR, and the plantarflexion angle and hip joint angular extension velocity increased in both groups. The force moment of ankle joint increased in experimental group, and the stiffness of lower limbs was significantly improved in both groups. Conclusions A 12-week GR exercise intervention model was successfully established, with 78% conversion rate (from rearfoot strike to forefoot strike). GR can effectively avoid the peak of impact force, reduce the maximum loading rate, increase the lower limb stiffness, and thus reduce or even avoid the risk of running injury caused by impact force and may provide a possibility for the improvement of running economy.