Left plantar pain is not necessarily a precursor to serious illness, it may be plantar fasciitis, flat feet, lumbar disc herniation, plantar fractures and other diseases. 1. Plantar Fasciitis: Long time walking or running will increase the load on the plantar fascia and increase the tension of the plantar fascia, which will easily lead to compression of the nerves at the fascia and cause plantar pain. 2. Flat feet: the collapse of the arch will change the weight-bearing force point of the sole of the foot, so that the load borne by the plantar fascia increases, which is easy to cause the sole of the foot to produce aseptic inflammation, and then appear the symptoms of pain in the soles of the feet. 3. Lumbar disc herniation: when the nucleus pulposus of the lumbar disc protrudes to the lateral fibrosis, it will press on the sciatic nerve, causing pain in the relevant areas innervated by the sciatic nerve, which in turn will cause pain in the soles of the feet. 4. Plantar fracture: when the left plantar fracture occurs, it will cause local soft tissue damage, inflammation, and make the plantar pain. Since there are many causes of left plantar pain, it is recommended to go to the orthopedic department of the hospital in time when the symptom occurs, and actively cooperate with the doctor for treatment.