To investigate the clinical features and strategy of diagnosis and treatment of patients with pelvic abscess and endometriosis. Methods: A retrospective analysis was performed on 70 patients with pelvic abscess from July 2014 to June 2019, which included 38 cases with endometriosis (in observation group) and 32 cases with simple pelvic abscess (in control group). The general condition, clinical characteristics, pathogen, treatment, prognosis, and outcomes of the patients were compared between the two groups. Results: There were no statistic significant differences in age, the situation of IUD used, the history of pelvic surgery, the diabetes situation , the temperature, the value of WBC, and the urinary symptoms of the patients between the two groups（P>0.05). There were statistic significant differences in the proportion of infertility (42.1% vs.18.8%), the levels of CRP (123.32±73.29mg/l vs.83.13±80.50mg/l), the diameter of the pelvic mass (7.76±5.70cm vs.4.25±4.05cm), the incidence of digestive system symptoms (44.7% vs. 18.8%), and the incidence of pelvic abscess during menstrual period (13.2% vs. 34.4%) of the patients between the two groups（P<0.05). There 3 patients with positive pathogene in the observation group, which were multi-drug resistant Escherichia coli, pseudomonas aeruginosa, and streptococcus. There were two patients with positive pathogene in the control group, which were all escherichia coli. There were no statistic significant differences in the time of returned to normal temperature and normal WBC, the time of abdominal pain disappearance, the hospitalization time, the rates of emergency surgery and recurrence of pelvic infection of the patients between the two groups（P>0.05). The rate of the secondary hospitalization surgery (39.5%) of the patients in the observation group was significantly higher than that (9.4%) of the patients in the control group (P<0.05). Conclusion: The patients with pelvic abscess and endometriosis have severe infection. It is advisable to use broad-spectrum antibacterial drug, especially those antibacterial drug is sensitive to Gram-negative bacilli. The patients cured by conservative treatment with intravenous antibacterial agents also have a high possibility of recurrence, often requiring the secondary surgery to completely remove the endometriosis lesions. It is should pay more attention to fertility situation of the patients during the postoperative following up.