Objective To detect the Enterococcus faecalis（E. faecalis） in post-treatment endodontic disease, and to analyze the relationship between the occurrence of E. faecalis and clinical symptom. Methods 108 teeth which need root canal retreatment were collected, and the clinical symptoms and physical signs were recorded. Bacterium samples from root canal were taken, and genome DNA from bacterial samples were extracted. The occurrence of E. faecalis by means of the polymerase chain reaction was investigated. Results The detection rate of E. faecalis in cases of root canal retreatment was 47.2%, while in cases with symptoms or signs, or cases with both symptoms and signs, the root canal E. faecalis detection rates were 52.6% , 57.9% , 62.5%. The detection rates of E. faecalis between cases with clinical symptom and without clinical symptom demonstrated statistical significance（P＜0.05）. The detection rates between cases with both clinical symptom and manifestly aneretic root and cases without clinical symptom and manifestly aneretic root had statistical significance（P＜0.05）. In the group of clinical symptom, the detection rate of E. faecalis in cases with biting pain was 66.7%, clearly higher than those without biting pain（P＜0.05）. Conclusion The occurrence of E. faecalis in cases of root canal retreatment correlates with clinical symptoms.
