Abstract: Objective To understand the value of lesion stability of chest radiograph as treatment completion criteria in smear positive TB treatment.Methods The chest X-ray films of smear positive TB patients cured in Yuanjiang county CDC from 2005 to 2012 were collected, and the changes of lesion were observed in 3, 6, 9,12,15,18 months after treatment, and the rate of drug withdrawal was analyzed, and median, M=P₅₀ on time of drug withdrawal was calculated.Results There were 85.0%(611/719) people whose focus had been reduced evidently in 719 new smear positive patients during the third month, and 194 patients stopped taking medicine after 6 months of treatment, and the rate of drug withdrawal was 27.0%(194/719),and 525 patients lengthened the treatment. The median of time on stabile foci is 11.09 months; There were 77.9%(67/86) people whose focus had been reduced evidently in 86 retreatment smear positive patients during the ninth month, and 18 patients stopped taking medicine after 9 months of treatment, and the rate of drug withdrawal was 20.9%(18/86), and 68 patients prolonged the treatment. The median time on stabile foci is 14.21 months.Conclusion That stabile foci as a standard to stop taking medicine is beneficial to TB thorough treatment.