Objective: To investigate clinical efficacy of using T-shaped incision of the hernia sac for separation of the giant hernia sac during transabdominal preperitoneal (TAPP) inguinal hernia repair. Methods: One-hundred and fifty eligible patients with giant oblique inguinal hernia scheduled to undergo TAPP during January 2013 to January 2016 in the Sixth Affiliated Hospital of Sun Yat-sen University were enrolled. Using a computer-generated random number table, the patients were randomly assigned to control group (76 cases) and study group (74 cases). Patients in control group underwent conventional separation of the hernia sac, and those in study group underwent T-shaped hernia sac incision and two directional dissection. The main clinical variables between the two groups were compared. Results: There were no significant differences in age, body index mass, time of onset, and size of the hernia defect between the two groups (all P>0.05). In study group compared with control group, the average time for hernia sac separation (8.3 min vs. 11.2 min), average intraoperative blood loss (2.1 mL vs. 4.3 mL), and average operative time (47.2 min vs. 51.3 min) were all significantly reduced (all P<0.05). No postoperative recurrence or mesh infection occurred in either group. The incidence of postoperative seroma in study group was significantly lower than that in control group (2.6% vs. 8.1%, P=0.029). The scores of visual analogue scale, length of hospital stay and hospitalization costs showed no significant difference between the two groups (all P>0.05). Conclusion: Using T-shaped incision of the hernia sac during TAPP separation of the giant hernia sac can effectively shorten the separation and operative time, and reduce the intraoperative blood loss, with no increase of incidence of postoperative complications.