Objective To explore the application of continuous posterior interscalene brachial plexus block (ISBPB) and patient-controlled intravenous analgesia (PCIA) in arthroscopic shoulder joint surgery and their influences on prognosis.Methods 128 patients underwent arthroscopic shoulder joint surgery were enrolled and divided into continuous posterior ISBPB group (group N, n = 64) and PCIA group (group I, n = 64) by random number table method. The pain visual analogue scale (VAS) in resting and active status were recorded at 6, 12, 24, 48 and 72 h after surgery. The levels of peripheral blood inflammatory factors and oxidative stress indexes were detected by ELISA before and 12 h and 24 h after surgery. The postoperative usage of opioid, adverse reactions, patients satisfaction and functional exercise of shoulder joint were recorded.Results VAS scores at resting and active status at 12, 24, 48 and 72 h after surgery in group N were significantly lower than those in group I (P < 0.05). At 12 h and 24 h after surgery, levels of serum interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and malondialdehyde (MDA) in group N were significantly lower than those in group I (P < 0.05), but there was no significant difference in SOD level between the two groups (P > 0.05). At 72 h after surgery, total dosage of opioid in group N was significantly fewer than that in group I (P < 0.05). The patients satisfaction rate in group N was significantly higher than that in group I (95.31% vs 79.69%) (P < 0.05). 1 month after surgery, score of American Shoulder and Elbow Surgeons (ASES) in group N was significantly higher than that in group I (P < 0.05). ASES score at 6 months after surgery was significantly higher than those at 1 month after surgery in both groups (P < 0.05).Conclusion The analgesic effect of continuous posterior ISBPB is good in arthroscopic shoulder joint surgery, which can reduce postoperative inflammatory reaction and promote postoperative recovery of shoulder function.