Objective: To investigate the analgesic effect of oxycodone combined with morphine on postoperative patient-controlled intravenous analgesia (PCIA) in elderly patients undergoing abdominal surgery. Methods: The perioperative data of 112 elderly patients undergoing abdominal surgery at Wuxi Ninth People’s Hospital from March 2020 to November 2021 were analyzed retrospectively. According to different postoperative PCIA analgesia schemes, they were divided into oxycodone group (52 cases) and combined group (morphine + oxycodone) (60 cases). The Visual Analogue Score (VAS), Ramsay sedation score satisfaction rate, PCIA usage and adverse anesthetic reactions were compared between the 2 groups. Results: At rest, the VAS scores at 12 and 24 h in the combined group were lower than those in the oxycodone group (P<0.05). In cough state, the VAS score of the combined group at 12, 24, and 48 h after operation was lower than that of the oxycodone group (P<0.05). There was no significant difference in sedation satisfaction rate between the 2 groups 12–48 h after operation (P>0.05). The use of opioids, the actual press and effective press times of PCIA in the combined group were less than those in the oxycodone group 48 h after operation (P<0.05). The adverse reaction rate of anesthesia in the combined group was 6.67% lower than 19.23% in the oxycodone group (P<0.05). Conclusion: Oxycodone combined with morphine has a significant analgesic effect on postoperative PCIA in elderly patients undergoing abdominal surgery. It can reduce the use of opioids and reduce the incidence of adverse anesthetic reactions, especially for postoperative PCIA in the elderly.