【Objective】 To reveal the variation law of black soil enzyme of Songliao Plain and provide reference to establish an effective fertilization system. 【Method】 Black soil under continuous maize cultivation was taken in the corn belt of Songliao Plain as materials. Enzyme activities in different areas and sections（“plant type ” and “wave type”） were determined based on field surveys and sampling correlation analyses between enzyme activities and soil nutrient contents were obtained.【Result and conclusion】 Soil enzyme acted as the biological catalyst in a soil cycle. The activities of different kinds of enzymes were significantly correlated with the soil nutrient, so enzyme activities could be used to indicate the soil fertility. Furthermore, urease could indicate the soil fertility well.