Fly ash, lithium slag and steel slag as industrial waste, replace quality cement to prepare cement mortar and concrete, but its utilization is often low, so using these industrial waste in large quantities by using X-ray diffraction (XRD), thermal analyzer, Fourier infrared spectrometer and scanning electron microscope analysis method, we studied the hydration products, spectral performance and microstructure of mortar after mineral admixtures as fine aggregate, and the change laws of mortar strength with the replacement rate (0%, 30%, 50%, 70% and 100%) were analyzed. Test results showed that the hydration products were CSH gel, Ca(OH)2, a small amount of AFt and Four kinds of slurry hydration products mainly for CSH gel, Ca(OH)2, a small amount of AFt and unhydrated particles (Al2O3 and SiO2) for cement paste, cement-lithium slag paste, cement-fly ash paste, cement-steel slag paste, which contain a certain Li2O·Al2O3·SiO2, Ca1.56SiO3.5·xH2O, and RO phase, respectively. Characteristic peak was 3 467, 3 438, 2 923, 2 348, 1 638, 1 429, 1 111, 1 000, 768, 696 and 462 cm-1 for four paste, but its strong peak was different and activity was also different, which was involved in the level of secondary hydration reaction is also different, so the content of Ca(OH)2 in cement-steel slag paste was significantly higher than cement-lithium slag paste and cement-fly ash paste. It played volcanic activity and filling effect when mineral admixtures replaced cement or fine aggregate. The flexural strength and compressive strength of mortar with 100% mineral admixture (lithium slag, fly ash and steel slag) were higher than pure cement mortar, it was about 37.77%/51.88%, 14.71%/11.70%, 14.71%/34.88%, respectively, But the flexural strength and compressive strength reached the maximum when the dosage of mineral admixtures was different. Therefore, mineral admixtures as fine aggregate of mortar were feasible, which can greatly improve the use of industrial waste in the concrete industry, and can achieve the result of energy conservation and emissions reduction.