This　experiment　designs　seven　fine　Grain　concrete　beams　HRBF500　bar.　By　changing　the　thickness　of　protective-covering,　longitudinal　reinforcement　ratio,　the　intension　of　concrete　etc,　the　experiment　analyzes　the　flexure　capacity　of　the　concrete　beams.　The　result　shows　that　the　measure　value　of　flexure　capacity　of　HRBF　500?bar　is　close　to　the　experiment　value,　and　it　suggestes　that　the　primary　calculate　mode　be　continued　to　be　adopted.