Stretchable　strain　sensors　of　conductive　hydrogels　have　been　widely　used　in　wearable　devices　and　soft　robotics.　These　applications　have　posed　combinational　requirements　for　hydrogels:　high　fatigue　resistance,　low　hysteresis,　and　high　electrical　sensitivity.　This　combination　is　hardly　realized.　Here　we　propose　a　composite　design　principle　to　fabricate　conductive　hydrogels　with　multiple　outstanding　properties　in　both　mechanical　and　electrical　tests.　One　phase　of　the　composite　hydrogel　is　a　regular　polyacrylamide　(PAAm)　hydrogel,　and　the　other　phase　is　a　highly　entangled　conductive　PAAm　hydrogel.　The　topological　polymer　network　of　each　hydrogel　phase　is　tuned　by　changing　the　density　of　the　crosslink　and　entanglement　to　achieve　different　mechanical　properties.　The　composite　hydrogel　shows　a　high　fatigue　threshold　(similar　to　330　J　m(-2)),　low　hysteresis　(＜3%),　high　resolution　(1%),　and　wide　range　(0-200%)　of　strain　sensing　capabilities.　In　particular,　hysteresis　is　one　order　of　magnitude　lower　than　that　of　reported　conductive　hydrogels　and　elastomers.　These　merits　qualify　the　strain　sensor　for　monitoring　cyclic　motion　signals,　such　as　bending　of　joints　(fingers,　wrists,　elbows,　and　knees),　moving　of　a　robotic　arm,　and　beating　of　a　porcine　heart　in　vitro.　The　resistance　of　the　sensor　changes　accordingly　with　the　beating　of　the　heart　for　500　cycles.　This　strain　sensor　of　composite　hydrogels　with　high　fatigue　resistance　and　low　hysteresis　may　open　new　opportunities　in　stretchable　electronics　and　soft　robotics.