Enlarged blood vessels on the dorsum of the left foot can be caused by normal physiological factors and abnormal lower limb lesions. 1. Normal physiological factors: If the enlarged blood vessels on the dorsum of the left foot are not combined with local edema, ulceration, skin color change and other abnormal manifestations, it is considered to be caused by normal physiological factors. It is mainly caused by the fact that the blood vessels at the dorsum of the foot are located at the most distal end of the body, which is subjected to greater venous pressure, as well as the weak skin of the dorsum of the foot, which is located in the superficial part of the blood vessels and other factors. 2. Abnormal lower limb diseases: when the left dorsal blood vessels are large, accompanied by swelling of the calf and foot, skin ulcers and color changes, it is necessary to consult a doctor, considering that it may be lower limb venous valvular insufficiency, the valve closure is not tight, which in turn causes high vascular pressure, and the blood vessels of the foot may appear tortuous, dilated, and skin nutritional disorders, and other abnormal manifestations. The enlarged blood vessels on the back of the left foot can be caused by normal factors and disease factors, and timely medical consultation is needed. Under the guidance of specialists, appropriate treatments should be carried out actively to help alleviate the uncomfortable symptoms as soon as possible.