Objective: To compare the effects of arthroscopic debridement and repair in treating Ellman grade II bursal-side partial-thickness rotator cuff tears.Methods: This is a single-center, prospective, randomized controlled trial. From September 2017 to April 2019, 78 patients underwent arthroscopic debridement (35 patients) or repair (43 patients) due to Ellman grade II bursal-side partial-thickness rotator cuff tears. Twenty-six men and 52 women were included in the study, with an average age of 56.31 years (range, 42 to 74 years). After the acromioplasty was formed, the debridement group only performed stump refreshing and surrounding soft tissue cleaning, while the repair group converted the partial tears into full-thickness tears and then sutured them by single row or suture bridge technique. The visual analogue scale (VAS), Constant-Murley shoulder (CMS), American Shoulder and Elbow Surgeons (ASES), and University of California, Los Angeles (UCLA) scores were used to evaluate clinical results preoperatively and at 6, 12, and 18 months postoperatively. Magnetic resonance imaging was used to assess the integrity of the rotator cuff, muscle atrophy, and fat infiltration.Results: A total of 85 patients met the inclusion criteria and were randomly divided into the debridement group (41 patients) and the repair group (43 patients). During the 18-month follow-up period, a total of seven patients were lost to follow-up. The functional scores of both groups were significantly improved: the VAS score decreased 5.06 and 4.63 in the debridement group (5.77 preoperative to 0.71 postoperative) and the repair group (5.49 to 0.86) (P < 0.05).