Objective To investigate the effect of CareDose 4D combined with Care kV on CT pulmonary ground glass nodule ( GGN) with respect to quality and radiation dose. Methods The thoracic model containing 6 GGN was performed by using 7 low-dose schemes. The CareDose 4D + Care kV was adopted in scheme 1. In schemes 2, 3 and 4, the tube voltage was 120 kV, and the tube current 30, 20 and 10 mAs respectively. In schemes 5, 6 and 7, the tube voltage was 100 kV, and the tube current was 30, 20 and 10 mAs, respectively. The image quality [ CT value, contrast noise ratio ( CNR) , noise value (SD) and subjective score] and effective dose (E) were compared. Results There was no statistically significant difference in CT value of GGN among different schemes (P>0. 05). The SD of scheme 1 was higher than those of schemes 2, 3 and 5, but lower than those f scheme 7, while the CNR of scheme 1 was lower than those of schemes 2, 3 and 5, but higher than that of scheme 7 ( t=13. 020, 9. 560, 8. 120,-5. 720, -7. 849, -5. 192, -4. 130, 1. 361,P<0. 05). SD and CNR of scheme 1 were not significantly different from those of scheme 4 and 6 ( P>0. 05) . The subjective scores of each GGN of schemes 1, 2, 3, 5 and 6 was over 3 points, but and the subjective scores of one GGN of each of schemes 4 and 7 were below 3 points. The value E of the scheme 1 was reduced by 63. 0％, 44. 4％, 38. 8％, and 9. 1％, compared with the schemes 2, 3, 5 and 6, respectively. Conclusions CareDose 4D combined with Care kV in low-dose lung CT scan can ensure the image quality of GGN and reduce the radiation dose effectively.