The present invention discloses a soft knee exoskeleton driven by a negative-pressure linear actuator, including: an exoskeleton controller, a left leg knee joint soft actuator, a right leg knee joint soft actuator and the like. The soft knee exoskeleton mainly uses a miniature vacuum negative pressure pump as an air pressure power source. A DSP embedded control system performs real-time processing on the data, such as a muscle force, a knee joint angle and a human-machine interaction force, detected by a sensing system, estimates a human-machine cooperation state, and performs real-time control on the switching of the negative pressure flow and an air channel of the miniature vacuum negative pressure pump.