One leg is thick and the other is thin for the following reasons: a. The thicker lower extremity may have local thrombosis or varicose veins, resulting in significant bruising of the lower extremity on that side, which is manifested as swelling and thickening of the lower extremity, accompanied by soreness and weakness of the lower extremity, and the patient will be significantly limited in walking, and the lesion in the blood vessel can be detected through ultrasound examination. Second, one side of the thinning muscle atrophy, such as the side of the lower limb fracture, dislocation or other bone, joint, muscle disorders, the patient needs a long period of brake rest, so the lower limb muscles will occur secondary atrophy, resulting in the side of the lower limb thinning, through careful physical examination can confirm the diagnosis. One leg is thick and the other is thin. Early diagnosis and treatment are necessary to restore symmetry to both lower limbs and to avoid the serious consequences of lower limb claudication.