To investigate the non-inferiority of ultrasound-guided rhomboid intercostal and subserratus plane (RISS) block compared to thoracic paravertebral block (TPVB) in postoperative analgesia for thoracoscopic surgeries. This study consecutively enrolled 50 patients undergoing elective thoracoscopic surgery. Following general anesthesia, the RISS group received a unilateral block with 40 mL of 0.25% ropivacaine, while the TPVB group received with 30 mL of 0.33% ropivacaine. The primary outcome measure was the 24-hour postoperative resting VAS score. Secondary outcome measures included nerve block operation time for two groups, postoperative 1, 2, 4, 8, 48-hour resting VAS scores, and different time points coughing VAS scores, time to first postoperative ambulation, total intravenous analgesic consumption at different time points postoperatively, complications related to the block. There were no significant statistical differences between the two groups in terms of postoperative rest and cough VAS scores at each time (P>0.05), and the mean difference in rest VAS scores did not exceed the non-inferiority margin in 95% CI. There were no significant differences in total intraoperative and postoperative analgesic consumption at different time points (P>0.05), and no significant differences in time to first postoperative ambulation (P>0.05). Compared to the TPVB group, the RISS group had a shorter nerve block operation time (259.43±30.11 vs. 335.23±30.96 s, P<0.001) and fewer instances of intraoperative hypotension (two vs. seven cases, P=0.022), bleeding at the puncture site, pneumothorax, and arrhythmia. In thoracoscopic surgeries, the postoperative analgesic efficacy of ultrasound-guided RISS block is not inferior to TPVB. Compared to TPVB, RISS block is simpler, quicker, and associated with fewer puncture-related complications.