Abstract: Based on probing experiments,three psychrotrophses culture mediums were discovered and utilized to culture bacilli,actinomyces,and mildew,respectively.Cultured pschrotrophses were separated and purified at 6℃.The physio-characteristics of psychrotrophses were identified and their nitration abilities were inspected by considering effects of pH and temperature.A best growth of psychrotrophses was detected when the pH value was in the range of 7 to 8.Biology fluorescence chromatography spectrum test indicates that all psychrotrophses present the maximal activity at 15℃,still have definite activity at 0℃,and lose natural metabolizing ability at above 35℃.Under the conditions of 6℃ and psychrotrophses dosage of 5.0%,the ammonia-nitrogen removal efficiencies of the three psychrotrophses are 57.7%,59.0%,and 58.7% respectively.If a mixture of psychrotrophses is applied under the same condition,the ammonia-nitrogen removal efficiency increases to 67.2%.