Abstract: Objective To evaluate the clinical quality of root canal therapy (RCT) in a three-stage dental specialist hospital in Hefei, and to analyze the effect of root filling on the curative effect of RCT on pulpal periapical disease, to help clinicians to judge the prognosis of teeth. To improve the treatment process and to provide a scientific basis for improving the curing rate. Methods In this study, 3 373 patients (3 766 cases of dental teeth) who underwent RCT from the department of endometriosis or endodermal diseases in the hospital from August, 2013 to November, 2013 were enrolled in this study. Their X-ray films were read independently by two senior oral radiologists, According to the results, the evaluation of root canal preparation and the quality of filling was made. From August, 2015 to November, 2016 we followed up those who got two years of RCT and evaluated the curing effects based on "root canal therapy technical specifications and efficacy evaluation criteria". Results The rate of filling was 78.81%, the rate of insufficient filling was 11.34%, the rate of overfilling was 9.85%, the omitting filling rate was 2.5%, the average course of treatment was (3.03±1.14) weeks. The total rate of root canal was 89.88%, and the average course of treatment was 2.7 weeks. The patients who completed our two years follow-up were 764 cases (852 teeth, the returning rate of 22.62%), and the success rate was 94.72%. Conclusion The filling rate of the posterior teeth was lower than that of the anterior teeth. The clinical efficacy of RCT depends on the filling operation. The insufficient filling has the lowest successful rate, and the filling has the best clinical effect. We should strictly abide by the normal operation of root canal treatment, reduce the number of root canal therapy, and improve the filling rate which aims to ensure the quality of RCT.