Hi, my 2 years old son sweaths a lot on his head, is it normal?

Probably: If your son's pediatrician has not found any abnormality of the thyroid or heart, and his weight is normal, then his perspiration of the head is probably normal for him. He may be more sensitive to a heated environment than are you. Try to keep his play area cooler and dress him less warmly. That alone may prove useful. Also, many toddlers are overdressed for bedtime which increases sweating.