Purpose Various approaches to serratus anterior plane (SAP) block have been discussed in the literature. The present study aimed to compare the analgesic efficacy and postoperative pulmonary function recovery of modified serratus anterior plane block (MSAP) and conventional serratus anterior plane block (CSAP) in patients undergoing videoassisted thoracoscopic surgery (VATS). Methods A total of 99 patients who underwent thoracoscopic surgery were randomly divided into three equal groups: a control group (C group) that received no block, a CSAP group that received preoperative conventional serratus anterior plane block, and an MSAP group that received preoperative modified serratus anterior plane block. The primary outcome was the first 24-hour tramadol consumption. The secondary outcomes were first-time-torescue analgesia, postoperative visual analogue score (VAS), postoperative respiratory function, and perioperative hemodynamics. Results The lowest tramadol consumption and longest time to first rescue analgesia were observed in the MSAP group. The postoperative VAS score at 2, 4, and 6 h was significantly greater in the control group, but it was comparable between the two block groups. At 8 h, the VAS score was the lowest in the MSAP group. At 12, 16, and 24 h, the VAS scores were comparable among the three groups. The MSAP group presented the best respiratory function during the first postoperative 8 h. Heart rate and mean arterial blood pressure were similar in both block groups but were greater in the control group during the intraoperative period. Conclusion The modified serratus anterior plane block is more efficient than the conventional serratus anterior plane block at reducing opioid consumption, prolonging rescue analgesic time, and improving pulmonary function recovery in patients undergoing video-assisted thoracoscopic surgery.