Underarm sweating in winter is considered to be related to physiological factors such as over-thickness of clothes, exercise and pathological factors such as hyperthyroidism and hyperhidrosis. 1. Physiological factors: due to the cold weather in winter, so people usually wear thicker clothes, or after exercise due to the body’s metabolic rate to speed up, increased heat production and the emergence of sweating all over the body, these are mostly considered as physiological factors, without special treatment. 2. Pathologic factors: (1) hyperthyroidism: for hyperthyroidism patients, due to high levels of thyroid hormones in the body, which in turn promotes the body’s metabolism, and sweating, body thinning, hand shaking and other discomforts. (2) Hyperhidrosis: its occurrence is related to genetics, vegetative nerve disorders, diet, drugs, diseases and other factors, and the patient mostly manifests as local or generalized excessive sweating, which can be combined with symptoms such as cold and clammy hands and feet, pale skin, etc. The patient may also suffer from excessive sweating in the armpits. For people with winter underarm sweating, it is recommended to go to a regular hospital if necessary, to clarify the cause of the disease under the guidance of the doctor to actively treat.