Abstract: The industrial processes of PVC, ethylene, and so on produced a significant amount of calcium carbide slag, leading to severe environmental issues and resource wastage. Acid leaching is a pre-treatment technique employed for extracting calcium from calcium carbide slag to produce high-value calcium-based chemicals like nano-calcium carbonate. However, impurity ions present in the slag are inevitably leached during this process, adversely affecting the purity of Ca²⁺. In the present study, HCl and NH₄Cl leaching systems were compared and the effect of various leaching conditions （molar ratio, temperature, agitation rate and time） on the leaching efficiencies of calcium and impurity ions （Al³⁺, Mg²⁺ and Fe³⁺） was investigated. One-way experiments, orthogonal experiments, and analysis using different characteristics were conducted. The findings revealed that the conversion rate of Ca²⁺ was higher in the HCl system compared to the NH₄Cl system. Amongst different leaching conditions studied here, molar ratio had the most significant influence on Ca²⁺ conversion rate followed by time > temperature > stirring rate. Leaching agent dosage emerged as the most influential factor affecting ion leaching in both systems while other factors exhibited small or even negligible effects. The HCl leaching system can leach Al³⁺, Mg²⁺ and Fe³⁺, while the NH₄Cl system can only leach Al³⁺ and Mg²⁺, and its concentration is much lower than the HCl system.