Abstract: Soil salinization is very serious in Hetao Inner Mongolia. The improvement of the saline soil becomes thus one of the most important issues for agriculture and environment. The combination of biological and chemical techniques has become a trend in improving saline soil. This paper is concerned on the improvement of saline soil fertility with combining biological and chemical techniques. The aim was to investigate the impacts of both desulfurization gypsum and oat on soil properties. The field experiment was set up in the sulfate saline soil at Hetao Inner Mongolia. The soil was amended with desulfurization gypsum (30 t/ hm²) and then grown with oat. The soil samples were collected following irrigation for washing salts. Both plant and soil samples were collected after harvesting oat. The oat plant was measured for dry matter and NPK contents. The soil samples were determined for pH, EC, salt ions, organic matter, total N and available NPK. The results showed that the irrigation in spring largely reduced the pH, electrical conductivity (EC) and salt ions in all the soil layers, more significant in surface. The values of pH and EC in surface soil had a reduction ranging from 14% to 17% and from 7% to 69% respectively. The main salt ions of Na⁺ and SO₄^2- were decreased by 80% and 39%. The desulfurization gypsum had not significant impacts on the salt washing. However, it had a potential improvement in oat growth, but negative impacts on NPK concentration of oat plant. The oat cultivation reduced markedly salt content, but little improvement on soil nutrients. Surprisingly, oat cultivation together with desulfurization gypsum addition could significantly enhance soil organic matter, available NPK, but little impacts on the reduction of salt ions, which might indicate there was a synergistic effect in improving saline soil fertility.