The working principle of the box filter press is composed of filter plates arranged to form filter chambers (with concave sides, two plates combined to form a box-shaped filter chamber).

The filter plate surface features ribs and bosses for supporting the filter cloth. There are holes at the center and corners of the filter plate, which, when assembled, form a complete passageway for introducing slurry, wash water, and extracting filtrate. Handles on both sides of the filter plates are supported on beams and tightly hold the plates in place with a clamping mechanism. The filter cloth between the plates serves as a seal.

Under the pressure of the feeding pump, the material liquid to be filtered is sent into each filter chamber, where it is separated from solid and liquid through a filter medium (suitable filter cloth selected according to different industries). Filtrate forms on the filter cloth until it fills the filter chamber, creating a filter cake. The filtrate passes through the filter cloth and flows into the outlet channel below the filter plate grooves, where it is discharged collectively. After filtering, clean water can be introduced to wash the filter cake. Sometimes, compressed air is introduced after washing to remove any remaining cleaning liquid. At the end of the filtration process, the pressure filter is opened to remove the filter cake (stored between adjacent filter plates), the filter cloth is cleaned, and the plate filter is re-tightened to begin the next working cycle.