Abstract: ob＜x＞jective To explore the application of dual-source CT semi-automatic mode combined with advanced model iterative reconstruction （ADMIRE） in low-dose thoracic CT. Methods A total of 500 patients who were scheduled to undergo chest CT were selected for the study. The patients were randomly divided into five groups with 100 patients in each group. F group was conventional dose group (tube voltage 120kV), filtered backprojection method (FBP) was used for reconstruction, A1~B2 group was low dose group (A1 and A2 tube voltage 80kV ,Bl and B2 tube voltage 70kV), A1 and B1 groups turned on semi-automatic mode (semi), ADMIRE (grade 3) was used for reconstruction, A2 and B2 groups turned off semi-automatic mode, other conditions were the same as A1 and B1 groups, and the image quality of routine group and low dose group was evaluated by subjective and ob＜x＞jective indexes. Results The SNR of A1, B1 and F groups was better than that of A2 and B2 groups. There were significant differences in CTDI (CT dose index), DLP and effectivedose (ED) b etween group F and low dose group. There was no difference in subjective evaluation of image quality in F~B1 group, but the worst in B2 group（P<0.05）. The artifact score of harness sclerosis in B1~B2 group was lower than that in F~A2 group, and the difference was statistically significant (P < 0.05). Conclusion In low-dose chest CT scanning, semi mode combined with ADMIRE algorithm can reduce the radiation dose while ensuring the image quality