<p>Facing the rapid development of the utilization of lithium resources, the accumulation of lithium slag produced by the spodumene sulfuric acid roasting method is increasing apace. For the sustainable development of the environment, it is of great significance to explore new technologies for bulk utilization of lithium slag. This paper uses a simple two-step hydrothermal method to convert lithium slag into ammonioleucite. The study found that, when the lithium slag is hydrothermally reacted with 2 mol/L Na₂CO₃ solution at 220℃ for 4&#xa0;h, an analcime with good crystallinity can be obtained. The analcime was hydrothermally reacted with 5 mol/L NH₄Cl solution at 130℃ for 24&#xa0;h to obtain ammonioleucite, and its conversion rate can reach an astonishing 99.1%. The hollow skeleton with which NH4⁺ can move makes the ammonioleucite have a good ion exchange specialty, which creates a foundation for it to become a high-quality slow-release fertilizer. This work is based on the large-scale and high-value-added utilization of lithium slag and provides an effective way to solve the environmental pollution problem caused by lithium slag accumulation.</p>