Objective　To provide anatomical basis for the functional reconstruction of the lumbar root after spinal cord injury.　Methods　Anatomical features of the lumbar roots were observed and summarized on 30 SD rats during the operation and on 10 SD rats microdissected after perfusion.　Results　There were six couples of the lumbar roots in SD rat. The L2-L4 roots mainly made up femoral nerve which dominating the quadriceps femoris. Sciatic nerve was composed of the L5-L6 roots which dominating the dorsal femoris muscle group. The lumbar medullary originated at the 12th thoracal vertebra and terminated at the 2th lumbar vertebra. The lumbar anterior root with one bunch was thin and its posterior root with two bunches was thick. Its anterior root and posterior root were wrapped together in one dura mater of spinal cord. The dura mater of spinal cord was thick and solid. The ventral and dorsal foots of spinal nerves were surrounded by meningeal tubes seperately till the point of dorsal root ganglion.　Conclusions　There are some difference in anatomical character of lumbar roots between SD rat and human.