Objective: To understand the similarities and differences in different dosage forms of tuberculin test for college students having close contact with tuberculosis in Nanning colleges and universities in order to provide reference for the prevention and control of tuberculosis. Methods: A total of 7 771 students were screened for symptoms and tuberculin skin test(TST)、X radiographs from 2018 to 2019 in Nanning.The used doses of Purified Protein Derivative of Tuberculin (TB-PPD) in 2018 and 2019 were 2 IU and 5 IU respectively. Results: A total of 916 positive cases were detected in 2 years, with the total positive rate of 11.79%. Total strong positive number was 184 and the strong positive rate was 2.37%. The number of tuberculosis patients was 17. Positive rate of the students from grade one to grade four was 13.88%, 8.57%, 10.59%, 10.29%, respectively. The difference was statistically significant(χ 2=46.30，P＜0.01). The positive rates of male and female in the past two years were 13.24%(500/3 777) and 10.42%(416/3 994), respectively (χ 2=17.84, P<0.01)，and there was no significant difference in the diagnosis of pulmonary tuberculosis among TST positive patients (χ 2=0.29,P=0.59). The positive and strong positive rates of 2 IU dose and 5 IU dose were 7.57%, 15.04%, respectively, the difference in dosage forms were statistically significant (χ 2=114.41,P<0.01). The tuberculosis case detection rate (CDR) of moderate & above positive subjects of 2 IU and 5 IU dose was 6.92% and 2.07%, respectively, the difference was statistically significant(χ 2=6.60，P=0.02). Conclusion More positive tuberculosis cases (including moderate & strong positive) can be detected by using 5 IU dose, though it is may not have advantage over discovering tuberculosis patients comparing to 2 IU dose. However, it is more critical to minimize the following cases and control the outbreak in university.