Abstract: 【Objective】 To provide a theological basis and the basic data on improving saline-alkali soil by natural grass growing techniques in orchard, the effects of this new grass management system on total soluble salt, organic matter, mineral elements concentration, enzyme activity in the soil, and fruit quality in pear orchards in the Yellow River delta were studied. 【Method】 The biochemical attributes of surface (0-20 cm) and sub-surface (20-40 cm) soil in the orchard with golden pear [Pyrus pyrifolia (Burm.f.).cv. Nakai] grown with grass for 2, 4, and 7 years, respectively, were compared with that of the clean cultivated pear orchard and their way of change was analyzed. The items were measured including soil total soluble salt, organic matter, minerals and enzyme activity. The quality of the fruits produced by those orchards was also compared. 【Result】 The results demonstrated that the naturally grown grass significantly increased the organic matter in different layers of the soil from the surface down to 40 cm while effectively decreased the total soluble salt. In pear orchard with 2 years grass growing, the nitrate nitrogen, available phosphate and potassium, exchangeable calcium and magnesium, effective zinc, copper, and ferrous in soil layer of 0-20 cm was significantly lower than that of the clean cultivated orchard, and 7 years grass growing made nitrate nitrogen, ammonium nitrogen, available phosphate and potassium, and effective zinc in the soil layer of 0-20 cm significantly higher than that of the clean cultivated orchard, while nitrogen, available phosphate and potassium, exchangeable calcium and magnesium, effective zinc, copper, and ferrous in the sub-surface soil layer was significantly lower than that of the control. And in the 7 years grass growing orchard, the urease activity in soil layer of 0-20 cm was 0.79 mg•g-1 and alkaline phosphatase was 1.25 mg•g-1, which was 3.8 times and 1.5 times of that of the control, respectively, but the two enzyme activities showed no difference in the layer of 20-40 cm. The fruit fracturability, soluble solids, total aroma, sugars, sugar-acid ratio of pear produced by the orchard with natural grass growing for 4 and 7 years were higher than those from the orchard that had natural grass orchard for 2 years. Correlation analysis indicated that the urease, phosphatase, sucrase, catalase and protease activities mostly showed very significant correlation with N, P, K, Mg and Zn in soil layer of 0-20 cm. The soil enzyme activity mostly showed no significant correlation with all the soil nutrients in layer of 20-40 cm, except the catalase.【Conclusion】 Natural grass could reduce the total soluble salt and increase the organic content obviously in 0-40 cm soil layer of pear orchards in the Yellow River delta. With year increasing, naturally grown grass could improve surface soil enzyme activity, content of mineral nutrition elements and enhance fruit fresh eating quality.