To discuss the effects of long-term chemical fertilizer application on enzyme activity and soil nutrients in arablemollisols of different organic matter contents,five organic matter contents were compared and analyzed based on the long-term experiment of mollisol productivity.The results showed that protease activities in mollisols increased with the increasingorganic mattercontents.Compared with non-fertilizationtreatment,the application of chemical fertilizer significantlyincreased protease activities in mollisols.Soil total nitrogen decreased with the decreasing organic matter contents in bothfertilizationtreatments,and the changes of available nitrogen was consistent with total nitrogencontents.Correlation analysisshowed that soil protease activities were significantly correlated with soil totalnitrogen,ammonium nitrogen and nitratenitrogen( P<0.05).Soil protease activity can be used as a sensitive indicator in evaluating the quality of mollisols under long-term application of chemical fertilizers.