Aiming　at　the　characteristics　of　the　asymmetric　hysteretic　performance　of　truss　string　structure,　and　considering　the　plastic　development　of　truss　string　structure.　The　experimental　model　of　the　truss　string　structure　was　established,　and　the　experimental　study　was　carried　out　under　cyclic　loading　with　vertical　amplitude　of　1:2　and　1:4.　The　difference　in　hysteretic　behavior　of　truss　string　structure　under　different　loading　systems　and　the　weak　position　of　the　structure　under　cyclic　loading　is　obtained,　and　the　results　were　compared　with　the　previous　study　of　cyclic　loading　test.　The　results　show　that　with　the　increase　of　cyclic　downward　loading　ratio,　the　downward　energy　consumption　of　the　truss　string　structure　increases　gradually,　and　the　failure　mode　changes　from　the　buckling　of　the　lower　chords　of　mid-span　to　the　buckling　of　the　upper　chords　of　mid-span,　which　eventually　leads　to　the　overall　instability　of　the　structure.　The　weak　positions　of　the　truss　string　structure　are　distributed　in　the　upper　and　lower　chord　members　of　the　truss　string　structure　in　mid-span.