Objective:To explore the ideal method of minimally invasive anterior lumbar extraperitoneal approach.Methods:Twenty-one adult embalmed cadavers underwent longitudinal incision near the left rectus abdominis, the extraperitoneal space and peritoneal characteristics were observed; the L 2-S 1 disc was exposed through extraperitoneal approach, and the relationship between the anterior large vessels and the disc was observed. One hundred adult abdominal CT were collected to measure the distance between the extraperitoneal fat of anterior abdominal wall and the rectus abdominis and the anterior midline at L 2-S 1 segment. One hundred and fifty adult lumbar MRI were collected to measure the distance between the anterior great vessels and the anterior midline of the intervertebral disc. Fifty-six cases of lumbar fusion were performed by minimally invasive anterior lumbar extraperitoneal approach, including 25 males and 31 females, aged 29-71 years. L 2-L 4 in 8 cases was performed by left rectus abdominis oblique incision, and L 4-S 1 in 48 cases was performed by median left transverse incision, with a length of about 8 cm, the complications related to the surgical approach were evaluated. Results:L 2-L 4 was proximal to the arcuate line, the posterior sheath of rectus abdominis adhered to the peritoneum, which was easy to rupture when separated; the peritoneum gradually thickened from the outer edge of the sheath of rectus abdominis and extraperitoneal fat appears. L 4-S 1 could be exposed distal to the arcuate line, the posterior side of rectus abdominis was extraperitoneal fat, the extension of arcuate line to the lateral abdominal wall would be slightly separated proximally, and there were multiple iliopsoas veins in the medial side of psoas major muscle. L 5S 1 was between the right common iliac artery and the left common iliac vein far, the median sacral vessel was small or absent, and the sympathetic nerve was to the left. Extraperitoneal fat appeared 36.2±9.9 mm, 35.2±11.6 mm and 27.6±11.2 mm away from the outer edge of rectus abdominis at L 2, 3, L 3, 4 and L 4, 5 segments respectively, and covered the posterior side of rectus abdominis and reached the midline at L 5S 1 segment. The left edge of abdominal aorta was 14.9±5.1 mm, 13.9±4.6 mm and 19.7±5.9 mm away from the midline at L 2, 3, L 3, 4 and L 4, 5 level respectively; the inferior vena cava was located on the right side of the midline at L 2, 3 and L 3, 4 level, crossed the midline 4.6±8.7 mm at L 4, 5 level. At L 5S 1 level, the left common iliac vein and the right common iliac artery were 14.6±6.8 mm and 17.6±5.3 mm away from the midline respectively. Seventy-six patients were successfully and fully exposed by small incision through extraperitoneal approach. 1 case of L 4, 5 had iliac lumbar vein tear and hemostasis with bipolar electrocoagulation. The operation time was 70-120 min, with an average of 90 min; Intraoperative bleeding was 15-70 ml, with an average of 30 ml. No severe complication such as nerve and great vessel injury occurred. Conclusion:Minimally invasive lumbar anterior retroperitoneal approach has small trauma and sufficient exposure with good feasibility. L 2-L 4 can be exposed with supine position and oblique incision next to the left rectus abdominis muscle, and L 4~S 1 with French position and median left transverse incision.