Abstract: Strawberry (Hokowasei) juice was clarified by ultrafiltration with different membranes ,including polysulphone (PS),sulfonated polysulphone (SPS)and polysulphone- sulfonated polysulphone(PS-SPS),aroma concentration was extracted in SDE(simultaneous Steam Distillation Extraction) method and determined by Gas Chromatography(GC) .The effect of ultrafiltration on aroma of strawberry juice and the causes of this effect were studied .Compared with SPS ,PS and PS-SPS were better in resistance of pollution and have high rate of water flow after cleaning .PS-SPS was better than PS in aroma retention, while retention of alcohols and acids was higher than esters. The causes of aroma loss were determined: absorption of membrane ,sieving of membrane ,volatilization during ultrafiltration.