objective: To study the value of low–dose Multi-slice CT（MSCT） in chest screening. Materials and Methods: From September to November in 2010,250 health people with routine chest screening randomly were divided into five groups including a control group (A) with conventional low-dose parameters and four study groups (B, C, D, E) with different ultra-low-dose parameters.Images of each group were evaluated by objective method (pattern noise) and subjective method (double-blind). Average values of CT dose index (CTDI) of each group were compared. There were significant differences among the images evaluated by pattern noise method, as well as among CTDIs of each group (P<0.05) . Result: Radiation dose were diminished by the biggest drop of 42% in group B to E, where image noises had no significantly increase,all images could be used for clinical diagnosis. Conclusion: chest MSCT with low-dose can be widely used in chest screening.