Provided are a negative oxygen ion purification new fan and an energy-saving and cost-lowering control mode. During working time, an intelligent controller controls the fan and a negative oxygen ion generator to work and drives the purification new fan to continue to convey purified fresh air simultaneously, and the negative oxygen ion generator continues to play roles of dust lowering, sterilization and health care; the intelligent controller can only control the fan to work, the negative oxygen ion generator does not work, the purification treatment of outdoor air in a physical filtration mode is achieved, and purified air with the PM2.5 pollution index being almost zero is generated continuously; the intelligent controller can control the fan not to work, and purification treatment in the physical filtration mode is stopped; meanwhile, the intelligent controller controls the negative oxygen ion generator to work, and the roles of dust lowering, sterilization and health care are played continuously; the three running modes are combined reasonably, on the condition that it is guaranteed that the air PM2.5 indexes in all rooms are normally excellent, and carbon dioxide does not exceed the standard, the service life of an air filtration unit can be prolonged, and the daily usage fee of equipment is lowered.