As high-energy charged particles from space, cosmic rays continue to bombard Earth’s atmosphere, which is one of the natural forcings affecting the atmosphere. Their flux is modulated by solar activity, the interplanetary magnetic field, and the geomagnetic field. High-energy particles carried by cosmic rays ionize the atmosphere and alter the horizontal and vertical structure of ozone and water vapor concentrations in the Upper Troposphere-Lower Stratosphere (UTLS) region through ion-molecular chemical processes, which may affect atmospheric composition and climate evolution on long time scales. In this paper, the research progress on the influence of cosmic rays on atmospheric composition is reviewed from four aspects: atmospheric ionization and conductivity characteristics, nitrogen oxide and free radical formation mechanisms, ozone response characteristics, and water vapor feedback pathways. Previous studies have shown that cosmic rays can generate active species such as NO _x and HO _x by inducing atmospheric ionization, produce opposite regional differences in stratospheric and tropospheric ozone, and may indirectly affect water vapor distribution by adjusting the vertical temperature structure and cloud microphysical processes. However, there remains significant uncertainty in the quantitative assessment of the impact of cosmic rays on atmospheric composition, and the characterization of key processes in relevant models needs improvement. Based on this, future research directions are outlined. Quantitative research on the multi-process coupling mechanism of “cosmic ray-ozone/water vapor-climate” should be strengthened, and more detailed ion chemical kinetics schemes and high-resolution climate-chemical simulations should be developed to deepen the systematic understanding of the role of cosmic rays as a natural forcing factor in changes in atmospheric composition.