[Objective] The growth and water utilization of dry farmland oats after the combined application of super absorbent polymer and microbial fertilizer were investigated, in order to provide an effective water-retaining and fertilizing measure for the crop production in Inner Mongolia of the Loess Plateau.[Methods] Four treatments, including no application of water retaining agent and microbial fertilizer (CK), single application of water retaining agent (A), single application of microbial fertilizer (M), combination of water retaining agent and microbial fertilizer (AM), were set up in the dryland area of the Loess Plateau, and the changes of soil water content, oat growth conditions, water consumption, yield composition and water use were analyzed.[Results] ① The combined application of super absorbent polymer and microbial fertilizer promoted the growth and development of oats. Taking the filling stage as an example, the plant height was increased by 3.27%-25.96%, the plant leaf-area was increased by 7.94%-23.06%, and the accumulation of aboveground dry matter was increased by 11.48%-21.88%. ② The combined application of super absorbent polymer and microbial fertilizer increased soil water content of 0-20 cm soil layer by 5.89%-11.50%, compared with no application. It significantly decreased soil water storage consumption by 7.70%-18.76% and reduced the total water consumption by 0.46%-1.26%. ③ The combined application of super absorbent polymer and microbial fertilizer promoted the formation of oat grains and biological yield, and thus promoted water use efficiency. The grain yield increased by 8.40%-20.12%, the biological yield increased by 10.80%-25.09%, and water use efficiency increased by 12.19%-26.80%.[Conclusion] The combined application of super absorbent polymer and microbial fertilizer can significantly promote the growth of oats in dryland, improve soil moisture status, conserve soil and water, and thus increase the yield of oats and improve the water use efficiency.