Objective:To observe the effect of two different apical surgery timing. Methods:68 patients with periapical lesion were divided into 2 groups. 30 patients( control group) were operated by apical surgery at least 1-2 months after root canal therapy( RCT) , while 38 patients(experimental group) were operated immediately after RCT. The patients were followed up 3, 6 and 12 months after apical surgery. Results:The curative effect analysed with the age, sex and tooth position showed no statistical difference between 2 groups(P>0. 05). Conclusion:Immediate and delayed apical surgery apical surger after RCT are similarly effective.