Numbness of the left foot due to lumbar disc bulge is caused by the patient’s disc tissue bulging to the back, the bulge to the spinal cord, intervertebral foramina, the spinal cord, nerve root pressure, and then cause the compressed nerves innervated by the left foot numbness. Numbness of the left foot is considered to be caused by the bulging disc tissue bulging out to the left posterior side, which causes pressure on the nerve root tissue on the left side, with the possibility of the 4th-5th lumbar disc and the lumbar 5-sacral 1 disc bulging out being the most likely ones. In addition to the numbness of the left foot, it is often accompanied by radiating pain, numbness and weakness of the left buttock, the back of the left thigh, and the anterior and lateral side of the calf. It is recommended that the patient go to the hospital to improve the auxiliary examination, such as lumbar CT, MRI, etc., in order to clarify the condition.