Abstract: Since the research field of calcium carbonate induced by freshwater algae in the plateau is still in the early stage of exploration, this paper focuses on the biological mineralization of freshwater algae on the rock surface under the unique environment of the plateau, and the characteristics and mechanical properties of the sediments induced by algae are analyzed with emphasis. By X-ray diffraction (XRD) test, it is confirmed that the sediment is mainly composed of calcium carbonate precipitation. Furthermore, the microstructure of calcium carbonate is observed by scanning electron microscopy (SEM), and the effect of calcium carbonate deposition on rock mechanical strength (compressive and tensile strength) is analyzed by point load test and Brazil splitting test. The results show that the freshwater algae can induce the production of calcium carbonate, and the induced calcium carbonate deposits have a certain mechanical strength, but the mechanical strength is weaker than that of the rocks attached to them, and the internal relationship between the microstructure characteristics of calcium carbonate deposits and their effects on the mechanical properties of rocks is revealed. As a new geotechnical discovery, calcium carbonate induced by freshwater algae in plateau environment can provide a scientific basis for understanding the potential role of biommineralization in rock weathering, sedimentation and geological engineering stability assessment.