A method for controlling gait-training apparatus using biofeedback is provided. A biosignal-detecting loop is used to detect and analyze the electromyographic signal of a user using the gait-training apparatus. A feedback control loop is used to drive the gait-training apparatus and determine the fatigue level of the user. When the user's muscle starts to become fatigue, the feedback control loop can further adjust the threshold for triggering the gait-training apparatus to retain the training session so that the training intensity can be regulated on-line and the user's muscle can be trained effectively based on the concept of progressive overload.