Abstract: A special strain (OCY-1) was screened from many types of yeast. The experiment revealed that OCY-1 can decrease NH3 emission 30% in the chicken manure. The optimal concentration of carbon resource, pH 6.0, temperature 35～C, 0.1 MKH～PO4, 0.1%MgSO.t～7H2O, 0.05% CaCl2 ? 2H～O and 0.1G NaC1 of OCY-1 was glucose. Nitrogen resources can be used widely, suggesting to use (NH4)2 SO4. The degrading mechanism of the NH3 was also studied. It was discovered that there is strong relation between the emission of ammonia and the remains of NH4+--N in chicken manure, but no relation to the remains of NO-3-N in chicken manure.