In order to evaluate the diagnostic value of the whole-blood interferon γ release assay (QuantiFERON TB Gold In-Tube test, QFT-GIT) in diagnosis of tuberculosis in children and adults in China (with a high rate of bacillus Calmette-Guérin vaccination and a high incidence of tuberculosis), 60 children and 60 adults with suspected tuberculosis were recruited for QFT-GIT test and clinical information collection. The results showed that among children, the sensitivity of QFT-GIT test was 83.87%, the specificity was 92%, positive predict value (PPV) was 92.86%, and negative predict value (NPV) was 82.14%. While among adults, the sensitivity of QFT-GIT test was 78.57%, the specificity was 84.62%, PPV was 84.62%, and NPV was 78.57%. Here comes a conclusion that QFT-GIT is of great value in diagnosis of tuberculosis, especially among children.