[Objective] The selection of soil ameliorant formula and the effect on soil fertility of maize field in Hexi irrigated area in Gansu Province were studied to provide technical support for the sustainable development of corn industry in this area. [Methods] A field experiment was conducted in a field base that had been used successively for maize seed production in the past 15 years, to select multi-functional ameliorant formula and to determine the corresponding agent content that have good effects on soil fertility improvement. The field is located in Hexi inland irrigated area of Jiuquan City, Gansu Province.[Results] The multi-functional content of agent formula had the following best combination: corn fertilizer, poval, organic waste group and aquasorb weight ratio is 0.032 2:0.001 4:0.965 5:0.000 9. Doses of the multi-function ameliorant and variables as seed corn field applying content of agent content, porosity, aggregate, water holding capacity, organic matter and available NPK, were significantly and positively correlated. It had significant and negative correlations with bulk density, pH value. As compared with traditional chemical fertilizer, application of multifunctional content of agent, seed corn field bulk density and pH value reduced 6.88% and 5.10% respectively; total porosity, capillary porosity, non-capillary porosity and aggregate increased by 10.46%, 10.49%, 10.48% and 11.75%; saturated water holding capacity, capillary water holding capacity and capillary moisture capacity respectively increased by 10.47%, 10.46% and 10.48%; organic matter, alkali-hydro nitrogen, available phosphorus and available potassium and cation exchange capacity(CEC) increased by 9.03%, 1.11%, 4.12%, 3.82% and 32.03%; fungi, bacteria, actinomyces and bacteria amount respectively increased by 121.19%, 34.95%, 20.25% and 28.57%; Sucrase, urease, phosphatase, and polyphenol oxidase respectively increased by 44.74%, 44.73%, 38.46% and 62.50%. [Conclusion] Application of multi-functional content of agent can improve seed corn field profiting from the improved physio-chemical and biological properties, and from the enhancement of soil enzyme activity and water holding capacity.