The invention provides a water purifier, which comprises a raw water inlet, a pure water outlet, a pretreatment filter, a low-pressure switch, a raw water pressure meter, a water inlet electromagnetic valve, a pump entering pressure meter, a pressure boosting pump, a work pressure meter and a reverse osmosis membrane, wherein the pretreatment filter, the low-pressure switch, the raw water pressure meter, the water inlet electromagnetic valve, the pump entering pressure meter, the pressure boosting pump, the work pressure meter and the reverse osmosis membrane are positioned between the raw water inlet and the pure water outlet, the raw water pressure meter is connected between the low-pressure switch and the water inlet electromagnetic valve, the pump entering pressure meter is connected between the water inlet electromagnetic valve and the pressure boosting pump, and the work pressure meter is connected between the pressure boosting pump and the reverse osmosis membrane. The water purifier provided by the invention has the advantages that when equipment has faults, the fault reasons can be intuitively and accurately judged through display data of the raw water pressure meter, the pump entering pressure meter and the work pressure meter.