Pain in the lower part of the big toe on the sole of the foot may be caused by wear and tear, tenosynovitis, arthritis and other reasons. 1. Wear and tear: Wear and tear is mainly caused by long-term walking, running, ill-fitting shoes, etc. Due to localized irritation, pain in the lower part of the big toe on the sole of the foot may occur. 2. Tenosynovitis: it is a chronic aseptic inflammatory change of tendon sheath due to repeated mechanical friction, which may be related to improper posture, special occupational groups and other reasons. Due to the stimulation of inflammation, the phenomenon of pain in the lower part of the sole of the thumb may appear. 3. Arthritis: It may be due to inflammation, infection, trauma or other factors causing inflammatory joint lesions. Redness, swelling, heat, pain and dysfunction of joints may occur. Pain can also occur when arthritis develops in the lower part of the sole of the thumb. Pain in the lower part of the sole of the thumb can also be seen in other conditions, such as gout, etc. It is recommended to go to the hospital in time and follow the doctor’s instructions to avoid delaying the condition.