This research focus on the efficiency of Alpinia Oxyphylla Fructus in urine-reducing and developing the method of separating and identifying its active components. Established a mice model with diuresis to validate the Alpinia Oxyphylla Fructus’ different components and purified by varying measures in reducing urine. The total urine volume in the first 2 and 6 hours of the mice was collected by metabolic cage. The values of urine weight/body weight were calculated respectively. The result showed that 75% ethanol extract of ethyl acetate phase was the most sensitive part in urine-reducing. Four pure monomer compounds were further separate from this part by MCI and ODS-D columns, including two fatty acids. The structure of components were identified as (1) 3-methoxy-4-Hydroxy-diphenylhexane, (2)20-propyl-β-sitosterol, (3)oleic acid and(4) linoleic acid respectively, by the methods of NMR and other spectroscopy technology. Compound 1 and Compound 2 were separate from Alpinia Oxyphylla Fructus and confirmed to have effects on urine-reducing for the first time.