To investigate the biomechanical characteristics of the dominant and non-dominant sides of the lower limbs in the back kick technique, and to analyze the influencing factors affecting the completion rate of the back kick technique. The kinematics and dynamics data of 12 excellent taekwondo athletes from Wuhan Sports University were collected by VICON 3D motion capture system and KISTLER 3D force measuring platform. The paired sample T test was used to analyze the difference between the dominant side and the non-dominant side of the back kick technique. The results show that the peak hip flexion moment (P = 0.000) and peak power (P =0.006) of the non-dominant side of the attacking leg are higher than those of the dominant side, and the maximum abduction angular velocity (P = 0.014) of the dominant side is higher than that of the non-dominant side. The maximum hip extension angular velocity (P = 0.001) and peak extension power (P = 0.037) of the dominant side of the supporting leg are higher than those of the non-dominant side, and the peak flexion moment (P = 0.022) of the non-dominant side is higher than that of the dominant side. The maximum knee flexion angle (P=0.003) and the peak extension power (P = 0.044) of the dominant side of the attacking leg are greater than those of the non-dominant side. The maximum knee flexion angle (P = 0.006) and angular velocity (P = 0.018) of the dominant side of the supporting leg are greater than those of the non-dominant side, and the maximum knee extension angular velocity (P = 0.022) of the non-dominant side is greater than that of the dominant side. The maximum angular velocity (P = 0.005), peak power (P = 0.035), and peak torque (P = 0.005) of ankle plantar flexion on the dominant side of the supporting leg are greater than those on the non-dominant side. The striking speed of attacking leg (P = 0.002) and the strength value of electronic protector (P=0.015) on the dominant side are greater than those on the non-dominant side. It is concluded that in the knee raising phase, the time of knee raising on the dominant side is shorter, and the energy output of ankle plantarflexion on the dominant side and hip flexion on the non-dominant side is more. In the kicking phase, the power peak of hip and knee extension on the dominant side is larger, which could effectively improve the hitting speed. The speed and strength value of the dominant side are higher than those of the non-dominant side, and selecting the dominant side can improve the success rate of the back kick technique.