The invention discloses a geotrichum Fh5 strain which is preserved in the China General Microbiological Culture Collection Center called as CGMCC for short in May 4th, 2017. The preservation number is CGMCC No.13777. Besides, the invention further relates to application of the geotrichum strain. The geotrichum Fh5 strain can be used for effectively degrading sewage and ammonia nitrogen, with the concentration of 500 mg/L, in leachate and ammonia gas in odor; in the degradation process, nitrite nitrogen and nitrate nitrogen are not accumulated, and nitrification and denitrification can be synchronously carried out, so that the degrading rate of the sewage and the ammonia nitrogen in the leachate or odor reaches 100%, and the residual total nitrogen is 10 mg/L.