Abstract: Objective Strong acid leaching is the main measure taken in spodumene smelting, which has an important impact on the physicochemical properties of its smelting slags (lithium slags). To clarify the impact of acid leaching process on the cementitious activity of lithium slags and achieve large-scale consumption of lithium slags in the field of building materials, Method physicochemical properties of the two types of lithium slags and their effects on the mechanical properties and working properties of cement mortar were studied, and the influence mechanism of acid leaching process on the gelling activity of lithium slag was analyzed by combining XRD, TG-DTG, FT-ID and MIP test methods. Result The most suitable lithium slag content in the cementitious system is 20%, and the mechanical properties of the NLS group mortar are generally higher than those of SLS. At 7～14 d, NLS quickly participated in the volcanic ash reaction, inducing hydration products such as calcium aluminosilicate (C-A-S-H) gel and calcium silicate hydrate (C-S-H), thereby densifying the pore structure and promoting the development of mechanical properties of the sample. Conclusion The amorphous phase material with relatively low content in SLS also participated in the volcanic ash reaction in the later stage, but due to the high content of SO₃, more AFt and other products were formed, which had a certain negative impact on the sample.