Abstract: Objective To evaluate the value of DR in close contacts investigation in outbreak of tuberculosis. Methods Both DR and CT were taken to screen close contacts(35 cases) from the event of tuberculosis outbreak in May,2014,the missed detection of different kinds of lesion and hidden parts were evaluated with Chi-square test and area under ROC curve. Results Abnormal shadow detection rate of CT was 40.0%(14/35), and it was significantly higher than 22.9%(8/35)of DR,χ² value was 16.154, P<0.01. In missed 6 cases with DR,due to anatomic conceal site accounted for 3 cases,such as hilar(1 case),azygos vein esophagus crypt(1 case) and thickening of the blood vessels in the lower lobe(1 case). Other reasons accounted for 50.0%. Early tree-in-bud signs were the major signs in missed cases. ROC analysis showed that the lesions, which the length of the major axis(cut off value) was not more than 22 mm, were undetected easily. Area under curve(AUC) was 0.925. The sensitivity and specificity were 90.0% and 83.3%, respectively. In 12 cases with abnormal shadow were detected by CT, lesions involving in one lung segment to more than five lung segments were 7 cases (58.3%), 2 cases (16.7%), 1 case (8.3%), 1 case (8.3%), and 2 cases (16.7%),respectively. Percentage of cases that involved less than one sub-segment was 41.7%(5/12). Frequency of lesions involved in the upper lobe,the mid-lingual lobe, and the lower lobe were 66.7%(8/12),16.7% (2/12) and 50.0% (6/12),respectively. CT images showed cavity-air spread type in the index case,and mainly including cavity and tree-in-bud sign.Tree in bud signs, which accounted for 91.7% (11/12), were the main CT characteristics in active pulmonary tuberculosis(PTB) among close contacts. All 4 cases of pleurisy patients appeared pleural tuberculoma after 3-4 months chemotherapy, and showed the same image characteristics. Six cases with micro-lesions were taken by anti-TB experimental treatment, the lesions of 2 cases was significantly absorbed after 2 months, and all the 6 cases absorbed after 6 months. Conclusion CT is more valuable in the screen of TB outbreak in school compared with DR. Subclinical cases detected by CT is recommended to take a formal anti-TB treatment.