Abstract: All fascia between the transversalis fascia of anterior abdominal wall and the peritoneum can be called the preperitoneal fascia clinically. According to the interfascial plane theory, the preperitoneal fascia is a multilayer structure, and preperitoneal space was divided into two surgical planes including parietal and visceral by its membrane layers. Surgical planes of totally extraperitoneal herniorraphy (TEP) can be described as follow: for median region, surgery can be performed in parietal plane, that is avascular region filled with loose areolar tissues between the transversalis fascia and the preperitoneal fascia, which is called “holy plane” of TEP. For Doom region,surgery is transferred into viscecal plane, which is between the preperitoneal fascia and the peritoneum, due to the particularity of spermatic cord through the abdominal wall. For lateral region, the abdominal wall restores to normal structure, and surgery can be performed in parietal plane or viscecal plane. The preperitoneal fascia needs to be dissected during the transfer from parietal plane to viscecal plane. The concept of plane transformation can explain the formation mechanism of preperitoneal loop and no connection between Reztius space and Bogros space. The author has elucidated the significance of preperitoneal fascial anatomy of anterior abdominal wall in TEP based on clinical experience of TEP and authoritative literatures.