The invention discloses a ventilation system including an inner, an outer tube and an air intake and exhaust apparatus. The inner tube has one end extending in a radial direction, wherein an air outlet and an air outlet are formed on the inner tube. An exhaust channel is formed between the inner and outer tubes, and the supporting member is disposed in the exhaust channel. The air intake and exhaust apparatus comprises an elevating member, a plurality of driving members and a cover plate. The elevating member has a connection block. The driving members are made of expandable material. The cover plate is rotatably coupled with the inner tube and has a connection portion. The connection portion abuts against the connection block when the driving members are not expanding. The connection portion of the cover plate disengages from the connection block when the driving members are expanding.