This paper introduces a novel and light weight lower extremity exoskeleton, used for carrying heavy load in the individual soldier combat system. This exoskeleton has six degree of freedom per leg, only one of which is powered by the motor. In order to provide a reference for the exoskeleton mechanical structure and drive unit, the mechanical topology is designed and analyzed by Adams software to make a optimization and derive the drive joint kinematic parameters. Considering the safety and comfort for the wearers, a gravity balanced system has been designed in the hip joint to supply power for movement. The critical hardware arrangement aspects and control system are summarized.