This paper screened and followed up close contacts of active pulmonary tuberculosis to understand the latent infection and morbidity of close contacts and analyze related factors. It retrospectively analyzed the clinical data of patients with active pulmonary tuberculosis hospitalized in the tuberculosis ward of Wuxi No.5 People’s Hospital from March 2012 to August 2019, and analyzed and followed up the close contacts who had conducted the interferon-γ release assay (IGRA). A total of 39 active pulmonary tuberculosis patients under initial treatment and 74 close contacts were included in the analysis. Of all the 74 close contacts, 27 contacts were IGRA positive (36.5%) and 47 contacts were IGRA negative (63.5%). None of the 27 IGRA-positive close contacts progressed to active tuberculosis, but the differences between the two groups in terms of smoking (3/27 vs 0/47, P＝0.045), contact time with tuberculosis patients >5 h/d (22/27 vs 23 /47, P＝0.007), living in the same house (23/27 vs 20/47, P＝0.001) were statistically significant. Active tuberculosis patients corresponding to IGRA-positive close contacts and those corresponding to IGRA-negative close contacts were further compared, respectively, which found that the active TB patients corresponding to the IGRA positive group had more sputum smear tuberculosis bacteria load than that of the IGRA negative group (P＝0.019). Multivariate analysis showed that the amount of tuberculosis bacteria in sputum smear of tuberculosis patients was a significant factor influencing IGRA results of their close contacts. Close contacts of active pulmonary tuberculosis with higher sputum tuberculosis load are more likely to be IGRA positive.