A　soft　exoskeleton　for　the　hip　flexion,　named　H-Suit,　is　developed　to　improve　the　walking　endurance　of　lower　limbs,　delay　muscle　fatigue　and　reduce　the　activation　level　of　hip　flexors.　Based　on　the　kinematics　and　biomechanics　of　the　hip　joints,　the　ergonomic　design　of　the　H-Suit　system　is　clearly　presented　and　the　prototype　was　developed.　The　profile　of　the　auxiliary　forces　is　planned　in　the　auxiliary　range　where　the　forces　start　at　the　minimum　hip　angle,　reach　the　maximum　(120　N)　and　end　at　90%　of　each　gait　cycle.　The　desired　displacements　of　the　traction　unit　which　consist　of　the　natural　and　elastic　displacements　of　the　steel　cables　are　obtained　by　the　experimental　method.　An　assistance　strategy　is　proposed　to　track　the　profile　of　the　auxiliary　forces　by　dynamically　adjusting　the　compensation　displacement　L-c　and　the　hold　time　Delta　t.　The　influences　of　the　variables　L-c　and　Delta　t　on　the　natural　gaits　and　auxiliary　forces　have　been　revealed　and　analyzed.　The　real　profile　of　the　auxiliary　forces　can　be　obtained　and　is　consistent　with　the　theoretical　one　by　the　proposed　assistance　strategy.　The　H-Suit　without　the　drive　unit　has　little　effect　on　the　EMG　signal　of　the　lower　limbs.　In　the　powered　condition,　the　H-Suit　can　delay　the　muscle　fatigue　of　the　lower　limbs.　The　average　rectified　value　(ARV)　slope　decreases　and　the　median　frequency　(MNF)　slope　increases　significantly.　Wearing　the　H-Suit　resulted　in　a　significant　reduction　of　the　vastus　lateralis　effort,　averaged　over　subjects　and　walking　speeds,　of　13.3　+/-　2.1%　(p　=　2　x　10(-5)).