In　order　to　analyze　the　influence　of　stochastic　pitting　corrosion　to　the　reliability　of　service　structure,　according　to　the　theory　of　extreme　values　of　random　variables　and　the　basic　theory　of　reliability　analysis,　the　reliability　of　flexural　concrete　member　based　on　the　randomness　of　pitting,　the　change　of　statistical　parameters　for　both　corroded　steel　bar　and　resistance　is　also　analyzed　based　on　the　randomness　of　pitting.　Based　on　the　checking　point　method,　the　development　law　of　reliability　of　concrete　bending　members　with　the　number　of　random　variables　and　the　service　life　are　studied.　The　results　indicat　that　the　influence　of　the　randomness　of　pitting　to　the　reliability　of　flexural　concrete　members　is　of　the　most　significance,　the　reliability　index　decline　with　the　increase　of　number　of　random　variables　and　the　service　life.　The　analysis　shows　that　research　presented　in　the　paper　can　provide　theoretical　basis　of　life　prediction.