To　analyze　the　complicated　structural　system　reliability,　based　on　classical　PNET　method　and　response　surface　method,　an　advanced　PNET　method　is　presented　in　this　paper.　The　system　reliability　of　a　ten-floors　steel　frame　structure　is　analyzed　using　the　advanced　PNET　method.　Results　show　that　exact　results　can　be　abtained　using　high　order　term　advanced　PNET　method,　and　the　calculation　time　is　shorter　than　using　Monte　Carlo　method.　The　new　method　effectively　reflects　the　correlation　between　failure　modes　of　the　structure　and　system,　and　better　reflects　the　structure　performance.