Objective: To evaluate the effect and safety of Kangfuyan Capsules (sic) for treating pelvic inflammatory disease (PID) in patients with chronic pelvic pain (CPP) in a multicenter, randomized, controlled, double-blind, parallel-group clinical trial. Methods: Totally, 240 PID patients with CPP were randomized into 2 groups using a computer generated random number at a 1:1 ratio from 10 hospitals in China between September 2014 and November 2015. Patients received either oral Kangfuyan Capsules or Gongyanping Capsules (sic, control); the regimen for both groups comprised 4 capsules (3 times daily) for 12 weeks, with follow-up visit 4 weeks after treatment. The visual analogue scale (VAS) scores, clinical responses, remarkable cure rates for each symptom, and quality of life scores were assessed at baseline, and after 1, 2, and 3 months. Adverse events were also recorded. Results: The VAS scores were significantly lower (P<0.05), whereas the clinical responses, remarkable cure rates for lower abdominal pain, uterine tenderness, adnexal mass, and adnexal tenderness, and Health-related quality of life (EQ-5D) scores were higher in the Kangfuyan group than in the control group at 3 months (P<0.05). Common treatment-related adverse events included high hepatic enzyme levels, reduced hemoglobin levels, and elevated platelet counts, although all the adverse events were either mild or moderate in severity. Conclusion: Compared with Gongyanping therapy, Kangfuyan therapy yielded markedly better analgesia effects for CPP caused by PID, with obvious long-term efficacy and good safety. (Registration No. ChiCTR190022732)