The self-management of acute postoperative pain is not well researched. This cross-sectional study investigates postoperative pain and pain self-management behavior. We recruited 127 patients who underwent total knee or total hip arthroplasty in an acute care hospital. We measured postoperative pain intensity and pain self-management behavior for three postoperative days. The results showed that the participants experienced mild and moderate pain intensity and perceived moderate to severe pain interference, which influenced their mood, sleep patterns, ability to walk, and performance of general activities and rehabilitation exercises. Female participants reported significantly higher pain intensity and lower pain self-management behavior; highly educated participants reported significantly lower pain intensity and higher self-management behavior. Pain intensity scores had a significant negative correlation with the total self-management behavior score (r = −0.719, P < .01). Health care professionals must consider patients’ demographic characteristics when providing education and support regarding pain self-management for postoperative pain control.