The　length　error　of　members　is　the　most　important　factor　in　the　initial　formation　and　pretension　deviations　of　cable-truss　structures.We　conducted　random　tests　of　the　radial　cable　length　in　the　cable-truss　structure　of　spokes　with　a　designed　span　of　6m.Based　on　the　reliability　theory,　we　used　the　response　surface　and　Monte　Carlo　methods　to　obtain　a　reliability　index　for　different　working　conditions.Lastly,　we　obtained　a　reliability　fitting　equation　and　the　sensitivities　of　different　structural　parameters.The　results　show　that　random　errors　in　radial　cables　considerably　influence　the　reliability　of　the　structure.　©　2019,　Editorial　Board　of　Journal　of　Tianjin　University(Science　and　Technology).　All　right　reserved.