The plate-type primary filter is a kind of air filter with simple structure and low price. It is used for the pre-filtration and purification of the air-conditioning system in relatively clean places, and the comfortable air-conditioning system has low requirements. Filter efficiency G3-G4. The filter material of the plate-type primary filter is fluffy needle-punched non-woven fabric or glass fiber material, and the outer frame is galvanized steel sheet, aluminum profile, etc. Common frame widths are 595mm, 493mm, 290mm, 391mm, 442mm, 620mm, and the thickness of the plate-type primary filter is 46mm, 96mm, 21mm.