Objective To investigate the impact of parameters setting on image quality and radiation dose of low-dose chest CT scanning when iCT tube current was set as 17 mAs.Methods Two hundred volunteers who accepted low-dose chest CT screening with tube current was set as 17 mAs were randomly divided into four groups according to the tube voltage and automatic exposure control (DoseRight) settings (group A:120 kV,DoseRight;group B:100 kV,DoseRight;group C:120 kV,fixed tube current;group D:100 kV,fixed tube current).Then hybrid iterative reconstruction (HIR:iDose4) and iterative model reconstruction (IMR) were performed on all scanned images of lung and mediastinal window algorithm,respectively.The effective dose and image quality of 4 groups were compared.Results There were significant differences of image quality score and effective dose among 4 groups.The image quality of group A and B were better than that of group C (P＜0.05),and of group D was the worst compared with the other three groups (P＜0.05).Image quality scores of the mediastinal window of group C and D and the lung window of group D at iDose4 reconstruction were lower.SNR value of group A,B,C,D decreased in order (P＜0.01).Group A had the highest effective dose (P＜0.01),while the effective dose of group B and group C had no significant difference (P=0.055),and group D had the lowest effective dose (P＜ 0.01).Conclusion When tube current was set as 17mAs at iCT,selecting 100 kV tube voltage,DoseRight and IMR reconstruction arithmetic can obtain satisfactory image quality and low radiation dose.