Black patches on the soles of the feet are considered to be pigmented nevus, bruises caused by trauma, melanoma and so on. 1. Pigmented nevus: pigmented nevus may be congenital or formed later in life, and the nevus formed later in life is basically less than 6mm, which may be a patchy rash or a papule, and generally has clear boundaries without pain, itching and other uncomfortable symptoms. 2. Bruising caused by trauma: If there is trauma on the soles of the feet, such as stepping on some hard objects, it will cause a small amount of bleeding of subcutaneous blood vessels, and then there will be black patches. 3. Melanoma: Melanoma is a malignant tumor formed by malignant transformation of melanin cells, which initially manifests itself as black plaque, but this plaque grows faster, and it will be gradually elevated, and the shape and color will be changed, and the further development of melanoma will result in ulcers, which will not be healed again and again, and this is a kind of more dangerous disease, which should be treated as early as possible. Black plaques on the soles of the feet may also be due to other reasons, it is recommended to go to the regular hospital in time, by the specialist to clarify the cause and standardize the treatment.