Objective To explore the feasibility of children age dependent chest tube voltage settings for optimizing radiation dose and image quality in digital radiography (DR). Methods Children aged 0 to 14 who visited the First Affiliated Hospital of Xinjiang Medical University from January, 2008 to December, 2010, were divided into the following 5 age groups: 0~, 1~, 3~, 7~, and 11~14-year-old, and each group was then randomly assigned to the optimization and control groups to take DR by computer. DR in automatic exposure control with different tube voltage depending on children age; the control group: DR in automatic exposure control with conventional fixed tube voltage. The dose area product (DAP) was adopted for the measurement of radiation dose, while the visual grading analysis score (VGAS) was for image quality. Then SPSS 17.0 was applied for statistical analysis. Results A total of 2 450 children were initially included. Finally there were 2 415 children included in the anteroposterior chest image in this study, and the other 35 children were excluded for their anatomical characteristics could not be showed due to serious primary diseases. There were 1 202 patients in the optimization group and 1 213 patients in the controlled group. The mean DAP in the optimization group was lower than that in the control group with a significant difference (t= –4.967, P=0.008). The mean VGAS in the optimization group was higher than that in the control group with a significant difference (t= 23.738, P=0.000). Conclusion Children age dependent tube voltage settings can effectively reduce radiation dose and improve image quality at the same time.