Objective To analyze the incidence and possible risk factors of the chronic postsurgical pain (CPSP) in patients undergoing cardiac surgery with cardiopulmonary bypass via median sternotomy. Methods A total of 248 cardiac surgery patients (104 males, 144 females with age of 20–74 years) were enrolled in this single-center, prospective observational study. The severity of acute postoperative pain at first 7 days was evaluated by numeric rating scale (NRS) and pain at 30 days after surgery and CPSP at 3 and 6 months after surgery was evaluated with modified brief pain inventory. Results The CPSP at postoperative 6 months occurred in 45.2% (112/248) patients and 24.1% of them suffered moderate to severe pain (NRS≥4). The CPSP at postoperative 3 months occurred in 60.9% (151/248) patients and 25.8% of them suffered moderate to severe pain. Moderate to severe postoperative pain at postoperative 30 days and 3 months, and intraoperative remifentanil infusion were the risk factors of the CPSP at postoperative 6 months. Conclusion CPSP is common in patients undergoing cardiac surgery with median sternotomy. Moderate to severe postoperative pain at 30 days and 3 months, and intraoperative remifentanil infusion can predict the presence of CPSP at 6 months.