In　a　thin-walled　UHPC　structure,　which　thickness　is　less　than　three　times　of　fiber　length,　steel　fibers　are　randomly　distributed　in　two-dimension　(2D),　which　affects　the　tensile　properties.　This　study　presents　an　analytical　model　based　on　2D　random　distribution　of　steel　fiber　for　predicting　the　tensile　properties　of　thin-walled　UHPC　structures.　A　probability　distribution　model　is　introduced　to　determine　the　number　of　fibers　at　the　cracking　surface　with　a　character　coefficient　of　2.55.　Residual　tensile　strength　and　energy　dissipation　of　the　thin-walled　UHPC　specimen　at　the　post-cracking　stage　are　determined　addressing　the　combined　effect　of　fiber　bridging　effect　and　tension　softening　behavior.　The　validity　of　the　proposed　model　is　verified　by　comparing　it　to　uniaxial　tensile　test　results　of　UHPC　specimens　with　various　thicknesses.　An　analytical　study　result　shows　that　the　bridging　effect　of　fiber　is　affected　by　the　fiber　content　and　aspect　ratio.　A　theoretical　equation　with　a　recommended　coefficient　of　0.266　is　proposed　to　determine　the　aspect　ratio　of　steel　fiber　to　avoid　the　rupture　of　fiber　during　the　pullout　process.