The invention discloses a water purifier, which comprises a water treatment unit, a Wifi communication module, a sensor and a controller, wherein the water treatment unit comprises a pure water fabrication device and a tail water/pure water storage device; the pure water fabrication device comprises a UF purification film filter core 1, a first flush valve 2, a low-voltage switch 3, a carbon fiber filter core 4, a first flush valve 5, an ultrafiltration water valve 6, a booster pump 7, an RO film filter core 8 and a third flush valve 9; the tail water/pure water storage device comprises a storage tank 15, a first check valve 10, a second check valve 11, a tail water proportional valve 12, a second high-voltage valve 14 and a first high-voltage valve 13; and the storage tank 15 comprises a pure water storage part 16 and a tail water storage part 17. By the technology, an intelligent, simple, compact, safe and convenient water purifier which is capable of saving water resources and achieving high-intelligence and long-term purification and is high in water preparation amount and free of tail water loss is provided.