There are many causes of left calf numbness, the most common of which are lumbar spine disease, sciatic nerve disease, left leg artery and vein obstruction, left leg nerve injury, etc., as follows: 1, lumbar spine disease: patients who have lumbar spinal stenosis, lumbar disc herniation, lumbar spine slippage, intra-vertebral tumor, etc., which compress the left spinal nerve root, will lead to clinical symptoms of numbness in the left calf, and need to perform 2.Sciatic nerve disease: Patients with left sciatic neuritis and pear-shaped muscle syndrome may also have numbness in the left calf. 3.Obstruction of arteries and veins in the left leg: This may lead to a decrease in blood supply, which in turn may cause pain and numbness in the leg. 4.Nerve injury in the left leg: This may also lead to numbness in the left calf, which requires electromyography. Electromyography should be performed to clarify the diagnosis.