Tailings dams are unique growth environment for plants and contain a large amount of heavy metals in the soil, which affects plant physiology and ecology. To enhance endophytic fungal resources, we studied the endophytic fungi of Bothriochloa ischaemum living in copper tailings. Bothriochloa ischaemum was the dominant species in ‘eighteenth’ river tailings of the Northern Copper Mine. We collected live plants and separated the endophytes from the sheaths, and observed and described the endophyte characteristics and spore morphology. Simultaneously, we selected seven strains for actG, tefA, and tubB amplification, sequencing, and phylogenetic analysis. Our results showed that the endophytic fungus had a white colony and very slow growth rate. The spores were spherical and oval shaped, between 1.208 and 8.048 μm in size. Molecular identification identified the endophyte as Epichloë sibirica. We found that E. sibirica had a relatively high tolerance to several different heavy metals as follows:Zn²⁺ (120 mg/L), Cu²⁺ (160 mg/L), Pb²⁺ (240 mg/L), and Cd²⁺ (8 mg/L) based on experiments with different heavy metal concentrations. This study provided a theoretical basis for enriching endophytic resources and is of great significance to research of host resistance in the process of ecological restoration in copper mining areas.