BY series plate/frame filters adopt stainless steel multi-layer plate type filer pressing, and suit sealed filtering of the liquid with a concentration below than 50 percent, relatively low viscosity and a small quantity of dregs, so as to meet such requirements on purification, sterilization, clarification in semi-fine filtering an find filtering (if a micropore filtration membrane is directly selected, then it is allowed not to go across the micropore filtration membrane filter to achieve the purpose of sterile filtering). This unit is compact, flexible and easy to maintain; thus it has been widely utilized in such industries as pharmaceutical, chemical, foodstuffs and daily-use chemicals etc In addition, it is an indispensable filtering device in the pharmaceutical industry.