Objective: The biomechanical characteristics of lower extremity of competitive taekwondo athletes with during double roundhouse kick (DRK) were explored whenwhile usingthe electronic body protector (EBP) is used. Methods: Fourteen competitive taekwondo athletes were recruited to collect kinematic, kinetic and surface EMG data of the lower limb joints of the DRK action at the time of effective scoring using an electronic guard scoring system, sEMG testing equipment, 3D motion capture equipment and 3D force table, and use Visual3D software to calculate movement time, joint angle, ground reaction force and other data.The kinematic, kinetic and Surface electromyography (sEMG) data of lower limb joints during effective scoring of DRK action of 14 competitive taekwondo athletes were collected using 3D motion capture system, 3D force measurement table, sEMG test equipment and EBP, and the data were calculated using Visual3D software. Results: 1) The total time taken for two strikes of DRK was 0.583s, and the attacking time period of both dominant and non-dominant sides was the same. 2) The shift of center of gravity was smaller during the striking processkick, and both dominant and non-dominant sides had have good balance control abilitybetter control of striking balance. 3) There isare the same trends of changes in hip, knee, and ankle joint motion angles and angular velocities of the two sides. 4) The deficiency of the knee joint flexion angle of the attacking leg in the knee flexion phase before striking can be achieved by increaseing the extension angle velocityspeed in the extension phase and produce effective striking; In the knee flexion stage before hitting, the deficiency of the knee flexion angle of the attacking leg can be achieved by increasing the extension angular velocity in the extension stage (5) In the knee flexion and extension phases before striking, the medial head of the lower limb gastrocnemius muscle generates the most power both on two sides. Conclusion: The DRK technique has good continuity and left-right symmetry and is an important scoring tool in defensive counterattack. Athletes should strengthen the ankle joint flexibility, the strength training of lower limb gastrocnemius, and gluteus maximus and biceps femoris in the training process of DRK actionmovement, that unnecessary sports injuries will be avoided and in order more adaptableto adapt to the game mode using EBP.