Objective Aiming at reducing the restrictions on lower limbs imposed by traditional knee brace, a design scheme for knee brace complying with internal-external rotation is proposed. Methods By adding the internal-external hinge, the knee brace could help to release the degree of freedom (DOM) of internal-external rotation of the knee. In the experimental group, the subject was required to wear the bilateral unloading knee brace with or without internal-external hinges, respectively, while in the control group, the subject did not wear the knee brace. Then gait experiment and mechanical testing were conducted. Results In gait experiment, the bilateral unloading knee brace with internal-external hinges imposed less restriction on the knee than that from the knee brace without internal-external hinges, and it could also provide some distractive force for the knee joint. Conclusions The internal-external hinge design can help to reduce restrictions on the knee imposed from bilateral unloading knee brace.