Objective: To investigate the efficacy of laparoscopic percutaneous extraperitoneal closure (LEPC) for unilateral inguinal hernia in children, and effect of intraoperative laparoscopic exploration for finding contralateral patent processus vaginalis (CPPV) on prevention of the metachronous contralateral hernia (MCH). Methods: The clinical data of 161 children with unilateral inguinal hernia undergoing LPEC from January 2013 to December 2014 were retrospectively analyzed (observational group), and another 252 children with unilateral inguinal hernia undergoing open hernia repair from January 2010 to December 2012 were used as a historical control (control group). Patients in observational group received synchronous exploration of the inguinal region and had a ligation if CPPV was diagnosed, while exploration of the inguinal region was not performed in those in control group. The postoperative complications, hernia recurrence and MCH of the two groups as well as the influential factors for MCH were analyzed. Results: There was no statistical difference in incidence of postoperative complications and hernia recurrence between the two groups (both P>0.05), and MCH occurred in 13 cases in the whole group, of whom, one case occurred in observational group and 12 cases occurred in control group, and the difference had statistical significance (0.6% vs. 4.8%, P<0.05), further, 9 cases in control group occurred within postoperative 24 months. CPPV was found in 62 cases (38.5%) in observational group, which in age group of 0.5-<2 years reached 59.0% (23/39), and decreased with age increase. In control group, the incidence of MCH in of CPPV in cases with premature birth was significantly higher than in those with full-term birth (3.6% vs. 1.2%, P<0.05). Overall analysis demonstrated that MCH mainly occurred in male children undergoing open surgery with age less than 4 years and right inguinal hernia. Conclusion: LEPC has proven efficacy in treatment of unilateral inguinal hernia in children, and synchronous laparoscopic exploration for CPPV can reduce the incidence of MCH, which is particularly important for those with premature birth and age less than 4 years.