Objective To probe into the influence of magnesium sulfate combined with ropivacaine for transverse abdominis plane （TAP） block on postoperative analgesia after laparoscopic hysterectomy. Methods A total of 58 cases undergoing laparoscopic hysterectomy from November 2019 to November 2020 were selected and randomly divided into a control group （n=29） and a study group （n=29）. The patients of the two groups underwent bilateral TAP block. The control group was injected with 20 mL ropivacaine （0.375%）+2 mL normal saline in each side, and the study group was injected with 20 mL ropivacaine （0.375%） + 200 mg magnesium sulfate （10%） in each side. Then, the Visual Analogue Scale （VAS） score, total amount of morphine, time of first use of morphine, and adverse reactions were compared between the two groups. Results The VAS scores at postoperative 6 h, 8 h, and 12 h in the study group were lower than those in the control group （P<0.05）. The total amount of morphine used at postoperative 24 h in the study group was less than that in the control group, and the time of first use of analgesics was later （P<0.05）. There was no significant difference in the incidence of nausea and vomiting, restlessness, respiratory depression, and other adverse reactions at postoperative 24 h between the two groups （P>0.05）. Conclusion The effect of magnesium sulfate combined with ropivacaine for TAP block is ideal on postoperative analgesia after laparoscopic hysterectomy, because there are no serious adverse reactions, and less dependence on analgesics. It can reduce the dosage of opioids, and promote recovery of patients.