Coldness in one leg may be caused by physiological factors, or it may be caused by vascular lesions of the lower limbs, nerve compression and other pathological factors. 1. Physiological factors: may be a long time in the cold environment or mental tension and other factors, may cause capillary contraction, heat dissipation is reduced, manifested as cold legs. 2. Lower extremity vascular lesions: when the lower extremity arterial occlusion or deep vein thrombosis and other diseases, the lower extremity blood circulation is impaired, resulting in ischemia and hypoxia on one side of the leg, which leads to a leg cold. 3. Nerve compression: when there is lumbar spinal stenosis, lumbar disc herniation, there is nerve compression, one side of the leg has sensory loss, can also cause a leg cold. There are many causes of coldness in one leg, so it is recommended that patients be admitted to the hospital in time to find out the cause of the disease and carry out standardized treatment.