An air pollution prevention device applied for a baby carriage includes a sealing cover, a filtration cleaner, a gas detection module and an intelligent control and process device. The sealing cover is hooded on the baby carriage for forming a sealed space. The filtration cleaner penetrates the sealing cover form the outside of the baby carriage for introducing an outside air into the sealed space of the baby carriage and discharging an air pollution source out of the sealed space. The gas detection module detects the air pollution source and outputs gas detection data. The intelligent control and process device receives and compares the gas detection data and controls an enablement of a gas guider of the filtration cleaner for filtering and exchanging the air pollution source in the sealed space so as to generate a clean air.