The recovery of spent lithium-ion batteries is an unavoidable problem for the development of lithium-ion batteries industry. The effective recovery of spent lithium-ion batteries is of great importance to the sustainable development of lithium resources and the positive cycle of industry. At present, hydrometallurgy is the main method to recycle spent lithium-ion batteries. Alkaline leaching has better selective leaching ability for metal in electrode materials, and it is more efficient and cleaner in the recovery process and has excellent industrialization potential. Several methods of alkaline leaching are introduced in this paper, including ammonia leaching reductant system, ammonia leaching reductant hot working system, ammonia leaching reductant electrodeposition system, ammonia reductant leaching oxidation separation system, ammonia leaching reductant lithium-adsorption system. This paper briefly summarizes the recovery methods of spent lithium-ion batteries.