 The investigators select 500 subjects who meet the standard and are considered as study population I. Do specific gamma-interferon detection before the skin test, then inject intradermally with two dosage ESAT6-CFP10 and Tuberculin purified protein derivative TB-PPD at different arm of the same subject and get 192 participants whose three kinds of detection result are all negative and are considered as study population II.Then,they are immune to the Bacillus Calmette-Guerin BCG vaccine or the placebo of the BCG. Do specific gamma-interferon detection before the skin test, then inject intradermally with two dosage ESAT6-CFP10 and TB-PPD at different arm of the same subject 12 weeks after immunity.Negative rate of ESAT6-CFP10 after vaccination BCG as the main index , evaluate the specificity of different doses of ESAT6-CFP10, and conform the optimal dose of ESAT6-CFP10. 