The invention discloses a portable emergency water purifier. Particularly, the water purifier comprises a first shell, wherein a through hole is formed in the top of the first shell; a driving component arranged in the first shell, wherein the driving component comprises a screw rod, the screw rod passes through the through hole and extends outside the first shell, one end of the screw rod, extending into the inner part of the first shell, is provided with a pressing plate, the other end of the screw rod is provided with a knob, the knob is configured to drive the screw to rotate and push thepressing plate to move up and down in the first shell; and a filter component arranged at the bottom of the first shell, wherein the pressing plate and the filter component define a water inlet spacein the first shell. Therefore, the water purifier does not need an external power supply when in use, is convenient to carry, and is coupled with a pressurizing system, a filtering system and a disinfection system, and general sewage, river water, lake water and seawater can be used as water sources and can be purified to drinking water, the device can be used as an outdoor portable emergency water purification device.