BACKGROUND:: Reconstruction of motor function of limbs in spinal cord injury is significant for patients with paraplegia. OBJECTIVE:: To recover the innervations and muscle contraction function of quadriceps femoris in spinal cord injured rats by constructing the neural pathway using the ventral roots of spinal nerves above injured segment of spinal cord and lumbar nerve that dominates the quadriceps femoris. METHODS:: L1 ventral root was anatomized to L3 ventral root from Sprague-Dawley rats. After 6 months, axonal regeneration was found from L1 ventral root to L3 ventral root through the grafting nerve, which may reconstruct muscle contraction function. After nerve suture for 6 months, spinal cord injury was made in L2 segment for neuroelectrophysiology examination to observe innervation of quadriceps femoris. RESULTS AND CONCLUSION:: After semi-dissection of L2 segment, wave from quadriceps femoris was recorded in electromyogram meter when stimulating the grafting nerve. After injured the segment of L2, we also record wave from quadriceps femoris when stimulating L1 ventral root. Results showed that anastomosis of the L1 ventral roots of spinal nerves above injured segment of spinal cord and the ventral root below the injured spinal cord segment can reconstruct the reflex path of innervation of quadriceps femoris, and the reflex center of quadriceps femoris in the spinal cord moves up to L1 segment.