Abstract: Microbially induced calcium carbonate precipitation (MICP) is one widespread approach to soil clay improvement in sustainable biological engineering in the world. The green and efficient approach can also greatly contribute to a series of environmental and ecological challenges. Among them, urea-producing bacteria can be used to induce calcium carbonate precipitation for better soil consolidation. Bacterially generated urease enzymes can decompose the urea to further promote the binding of Ca2+ and CO32-. Therefore, the calcium carbonate precipitation can be expected to apply to desertification combating. However, the urea-producing bacteria can be limited to environmental adaptability and weak function in a harsh desert environment. Many technical bottlenecks are urgent issues for the sand-fixation using calcium carbonate precipitation induced by urea-producing bacteria. It is a high demand to develop native urea-producing bacteria. In the preliminary research, the strain of Sporosarcina pasteurii was identified from the aeolian soils in the Mu Us desert. In this research, the optimal reaction conditions were determined to verify the sand-fixation effect in the desert soil after optimization. A series of single-factor experiments were designed during 0-72 h with the different experimental gradients by pH (7, 8, 9, and 10), bacterial inoculum (1%, 2%, 3%, 4%, and 5%), the ratio of bacterial and cementing solution (25%, 50%, and 75%), and temperature (30, 35, and 40 ℃). The initial urease activity and calcium deposition rate were tested using the response surface method. The optimal reaction factors and conditions were then determined from the six factors (reaction time, pH, bacterial inoculum, the ratio of bacterial and cementing solution, reaction temperature, and initial urease activity). The sand-fixation experiments were carried out on the aeolian soil from the Mu Us desert under optimized conditions. Mineral morphologies and properties were then characterized by the scanning electron microscope (SEM). The thickness and hardness of the soil consolidated layer, soil particle distribution, soil organic matter and calcium carbonate content were measured to calculate the erodibility factor (EF) under soil wind erosion. The results showed that: 1) The main reaction drivers of calcium carbonate precipitation were determined as the reaction temperature, reaction time, pH value, as well as the ratio of bacterial and cementing solution. An optimal combination of conditions was achieved at 34.47 ℃, 71.68 h, pH 7.73, and 74.94% ratio. In this condition, the maximum rate of calcium deposition was 42.33%. 2) The calcium carbonate precipitation was obtained in the polycrystalline phase composition with the cubic, rhombic, spherical, and amorphous under the optimized conditions. Diverse calcium carbonate precipitation was formed on the surface of sand grains, or embedded in the sand grains. 3) Sand-fixation by induced calcium carbonate precipitation was significantly enhanced after optimization. The number of sand particles increased significantly (P<0.05), and the thickness and hardness of the soil consolidated layer increased by 5 and 10 times, respectively. The contents of organic matter and calcium carbonate increased significantly, whereas, the wind erodibility factor decreased in all times, which has the maximum reduction from 0.91 to 0.66 in 24 h. Therefore, the urea-producing bacteria-induced calcium carbonate precipitation can serve as the new effective and favorable sand fixation for desertification combating in the future. It is still necessary to develop the distribution of simultaneous ecological restoration, in order to gradually promote this new technology in large-scale field experiments. Consequently, in the field application, the sand fixation effect can be enhanced to further determine the application time and water under suitable conditions and the soil compaction will be avoided by appropriately breaking.