Abstract: Influence factors of high strength concrete made from lead-zinc tailings and slag powder were discussed by orthogonal tests.Hydration products and their microstructure were analyzed by XRD and SEM.The results showed that:①high strength concrete with the compressive strength of 93.75 MPa at 28 d were prepared when the slag was milled for 60 min（the specific surface 625.6 m²/kg)，and the mass ratio of the lead-zinc tailings to slag is 1 to 1 milling for 60 min（the specific surface 719.1 m²/kg)，and the gypsum accounts for 2% of the cementitious materials.The XRD spectrum and the SEM photograph indicated that the early strength of the concrete is derived from the AFt and the C-S-H gel generated increasingly during the curing time.Meanwhile the AFt closely surrounded by C-S-H gel contributed to the main strength increasing in later stage.②AFt will be constantly generated in the system when the dosage of gypsum is excessive，AFt surface will burst owing to absorbing to much water，and then the compressive strength of concrete is decreased.

Key words: Lead-zinc tailings, High strength concrete, Orthogonal test, XRD, SEM, Ettringite