The ventilation and air-conditioning system of modern buildings creates comfortable environmental conditions for people's work and life, but if the system is not designed properly, once a fire occurs, the criss-cross ventilation and air-conditioning ducts will become flames and smoke spread in the building It is an important way of transmission, and the consequences are extremely serious. In addition, as an important part of the building's life safety system, the smoke prevention and exhaust pipe also needs to work continuously during the fire to remove the high-temperature toxic smoke generated in time, prevent the smoke from spreading, and ensure the safety of personnel evacuation. Therefore, attention must be paid to the fire prevention treatment of ventilation and air conditioning pipes and the fire protection design of smoke prevention and exhaust pipes.