The invention relates to a water purifier capable of changing filter element components based on digitization and a monitoring setting method. The water purifier comprises a shell, wherein a display unit and an input unit are arranged on the shell, and a filter unit, a reversing unit, a detection chamber and a monitoring processing unit are arranged in the shell, wherein the filter unit comprises a plurality of filter element components; a plurality of sensors are arranged in the detection chamber; the input unit controls the reversing unit by virtue of the monitoring processing unit to change the direction of water flow passing through the filter element components; water quality signal of any one of the sensors, after being filtered by the filter element components, is transmitted to the monitoring processing unit; and through the monitoring processing unit, the processed signal is displayed on the display unit. Through the water purifier disclosed by the invention, a conventional way of estimating service condition of the filter element depending on time is changed into a way of directly displaying purification condition of the filter element through a display screen, and a user can change the filter element depending on different water quality demands.