A　two-stage　upflow　biological　aerated　filter　was　designed　as　an　advanced　treatment　process　to　optimize　the　operating　parameters　and　study　the　correlative　factors　influencing　the　efficiency　of　nitrification,　denitrification　and　phosphorus　removal.　The　experimental　results　showed　that　the　final　effluent　of　the　two-stage　upflow　biofilter　process　operated　in　series　could　meet　the　stringent　limits　of　the　reclaimed　water　for　the　total　nitrogen　of　2　mg/L,　and　total　phosphorus　of　0.3　mg/L.　The　high　treatment　efficiency　allowed　the　reactor　operating　at　very　high　hydraulic　loadings　and　reaching　nearly　complete　nitrification　and　denitrification.