The biological effects induced by low-dose ionizing radiation are complex and diverse. Radiation biomarkers and detection techniques often limit the studies. In this paper, Raman spectroscopy was applied to study the biological effects of low-dose radiation. Raman spectroscopy at 10 mW and 532 nm were used to analyze human neuroblastoma cells irradiated by X-ray at 100, 200 and 500 mGy. The DNA related Raman characteristic spectroscopic peaks of purine nucleotides (722～728, 1 572～1 581 cm-1, etc. ) and pyrimidine nucleotides (770～785 cm-1, etc.) were changed by ionizing radiation, indicating that low-dose X-ray irradiation caused changes in cell DNA level. Flow cytometry was used to analyze the cell cycle of human neuroblastoma cells cultured for 6 hours after irradiation under the same conditions. All three doses of X-ray ionizing radiation caused cell stagnation in the G2 phase of the cell cycle, which also suggested that ionizing radiation caused the increase of DNA level. Analysis of cell migration at 20 h after irradiation by scratch assay showed that human neuroblastoma cells exposed to all three doses of ionizing radiation showed reduced levels of migration compared to control cells not exposed to X-ray. Raman spectroscopy showed that low dose X-ray ionizing radiation induced changes in the DNA level of human neuroblastoma cells, and that was consistent with the cell cycle analysis and migration analysis, but the detection time was much earlier. Raman spectroscopy can be used to detect and monitor the early biological effects of low-dose radiation.