The hazards of secondhand smoke on children mainly include damage to the respiratory mucosa affecting the ventilation function, affecting the development of the nervous system and damage to other organs, etc. The specific analysis is as follows: 1. Respiratory system: second-hand smoke contains a variety of toxic substances, such as heavy metals, benzene, etc., these substances will cause damage to the mucous membrane of the respiratory tract and mucosal epithelial cells of the child, thus affecting the respiratory tract ventilation function. 2. Nervous system: Tobacco has volatile substances, such as nicotine, etc., will make the human body’s nerves in the state of excitement, long-term exposure will affect the development of the nervous system. 3. Other organs: the toxic and harmful substances in second-hand smoke will enter the blood circulation and reach other organs of the body, such as the liver, kidneys, heart, etc., thus causing damage. Secondhand smoke can jeopardize children’s health, so parents are advised to quit smoking in order to eliminate secondhand smoke.