Mid-deep geothermal reinjection technology is crucial for the sustainable development of geothermal resources, which has garnered significant attention and rapid growth in recent years. Currently, various geothermal reinjection technologies lag behind, lacking effective integration to address issues like low reinjection rates and thermal breakthrough. This paper reviews the basic principles and development history of mid-deep geothermal reinjection technology, focusing on various technical methods used in the process and analyzing their applicability, advantages, and disadvantages under different geological conditions. It highlights the unique challenges posed by deep geothermal resources, including high temperature, high pressure, high stress, chemical corrosion, and complex geological structures. Additionally, it addresses challenges in equipment selection and durability, system stability and operation safety, environmental impact, and sustainable development. Finally, the paper explores future directions for mid-deep geothermal reinjection technology, highlighting key areas for further research and potential pathways for technological innovation. This comprehensive analysis aims to accelerate the advancement of geothermal reinjection technology, offering essential guidance for the efficient reinjection and sustainable development of geothermal resources.