Abstract: Objective  To investigate the application effect of preoperative preemptive analgesia combined with nerve block guided by B-mode ultrasound for analgesia in children undergoing abdominal surgery during perioperative period. 
Methods  A total of 120 children undergoing abdominal surgery were selected as the research subjects， and then randomly divided into group A（preoperative preemptive analgesia group, n=30）， group B（nerve block guided by B-mode ultrasound for analgesia group, n=30）， group C（preoperative preemptive analgesia combined with nerve block guided by B-mode ultrasound for analgesia group, n=30） and group D（physiological saline group, n=30). The opioid dosage and pain severity at 2 h， 4 h， 12 h， 24 h and 48 h after surgery， hemodynamic indexes［mean arterial pressure(MAP) and heart rate（HR)］ before and after skin incision， resuscitation time and adverse reactions of four groups were compared. 
Results  The opioid dosage of four groups was increased over time，withe the lowest dosage in group C and the highest dosage in group D; the interaction between groups, time points and time points between groups showed statistically significant differences（P＜0.05）. The FLACC score increased initially and decreased afterward，with the minimal change in groups C and the maximal change in group D; the interaction between groups, time points and time points between groups showed statistically significant differences(P＜0.05). The MAP and HR of four groups after skin incision were all higher than those before skin incision; The MAP and HR of group C were significantly lower than those of groups A， B and D; the MAP and HR of groups A and B were significantly lower than those of group D, and there were statistically significant differences（P＜0.05）. No significant difference was found in the resuscitation time and adverse reaction rates of four groups(P＞0.05).  
Conclusion  The application effect of preoperative preemptive analgesia combined with nerve block guided by B-mode ultrasound for analgesia in children undergoing abdominal surgery during perioperative period is better， which is conductive to stabilization of hemodynamics and pain control. Therefore， it is of higher application value. 

Key words: analgesia, nerve block, abdominal surgery, perioperative period