Ｏｂｊｅｃｔｉｖｅ　To compare the efficacy of ultrasound guided transversus abdominis plane block(TAPB) and ilioinguinal/iliohypogastric nerve block(IINB) in providing postoperative analgesia after children groin surgery.　Methods　Eligible children, 2-4 years old (n=80), ASA Ⅰ, undergoing elective unilateral groin surgery, were randomly assigned into IINB group (ultrasound guided ilioinguinal-iliohypogastric nerve block after routine general anesthesia) and TAPB group (ultrasound guided transversus abdominis plane block after routine general anesthesia). Funk sedation scores, intraoperative HR, BP at time points of before induction (T1), skin incision(T2) and skin closure(T3), length of surgery, the time from PACU arrival to the first obtainable pain score, length of PACU stay, modified children's hospital of eastern ontario pain scale(m-CHEOPS) pain scores, pediatric anesthesia emergence delirium(PAED) scores, number of children with sufentanil administered in PACU, number of people occurred nausea and vomiting, satisfaction of parents were measured and recorded during the study.　Results　There was no significant difference in general characteristics, basic emotion score， local anesthetic dose and the haemodynamic parameter between the IINB group and TAPB group(P>0.05). However, the m-CHEOPS scores at the time points of first obtainable, 10, 20, 30 min in IINB group were lower than those in TAPB group(P<0.05), and the number of children received sufentanil administration in IINB group were less than in TAPB group[IINB group: 6 children (15%), TAPB group: 15 children(39%)](P＜0.05). There was no statistical significant difference in the occurrence rate of delirium between the two groups(P>0.05), whereas the PAED score of IINB group was lower than that in TAPB group[IINB group PAED score(median，inter-quartile range): 3(0-14), TAPB group PAED score: 6(0-16)] (P＜0.05). The occurrence rate of nausea and vomiting in IINB group were also lower than that in TAPB group, but there was no statistical difference(P>0.05).　Conclusions　Ultrasound guided IINB could provide more secure and efficient postoperative analgesia in children after groin surgery.