Performances　of　a　slow　sand　filter　used　in　tertiary　treatment　of　domestic　wastewater　were　evaluated　by　a　lab　scale　test.　Influent　and　effluent　COD,　turbidity,　color　and　total　bacterial　counts　were　analyzed　for　more　than　one　year.　All　results　showed　that,　performances　of　the　slow　sand　filter　were　nearly　the　same　with　its　filtration　rate　0.3　m/h　or　0.1　m/h.,　but　decreased　dramatically　when　its　filtration　rate　was　increased　to　0.5　m/h　from　0.3　m/h.　Temperature　decrease　had　a　significant　negative　effect　on　COD　removal　but　not　on　turbidity　or　bacterial　removal.　The　schmutzdecke　layer　contributed　more　than　half　quantities　of　pollutants　removal.　Average　effluent　of　COD,　turbidity,　color　and　total　bacterial　counts　were　34.9　mg/L,　0.6　NTU,　23.3°　and　6200　CFU/ml　respectively　and　corresponding　removal　rates　were　43.9%,　89.5%,　55.6%　and　73.5%　under　filtration　rate　0.1　m/h　in　Summer.　©2010　IEEE.