Aiming at the gait instability phenomenon under disturbed conditions, domestic and foreign scholars have done some research works, but the relationship between the independent balancing act with the surface electromyographic and gait parameters in the process of instability has yet rarely been involved. In this study, using the gait analysis combined with electromyographic signal analysis, we investigated balance adjustment mechanism of joints and muscles of the human lower limb under the condition of walking on the level trail and after foot heel touching the ground and unexpected sliding. Studying 10 healthy subjects with the unified shoes, we acquired and analyzed the changing rule of the lower limb joint torque, joint angle, and the surface electromyographic of the main muscle groups involved in situations of dry or oid trails. Studies showed that when accident sliding happened, the body would increase ankle dorsiflexion torque moment, knee unbend torque and straight angle, and meanwhile increase the torque of hip extension, and timely adjust muscle activation time (Followed by activation of Tibialis anterior muscle→Rectus femoris→Gastrocnemius→Femoral biceps) to adjust the center of gravity, to maintain balance of the body, and to avoid falling down. The results of the research could be used to explore new ideas and to provide a certain reference value for preventing slip damage, rehabilitation training and development of lower limb walker.