The invention discloses a pressure filter comprising a plurality of filtering plate sets which are connected in sequence, wherein each filtering plate set comprises a main plate, an auxiliary plate, and an auxiliary frame, the auxiliary plate is fixed on one side of the main plate and on the same side of the main plate, the auxiliary frame is sleeved on the periphery of the auxiliary plate in a sliding mode, and the other side of the main plate is connected with the auxiliary frame of the adjacent filtering plate sets. Moreover, volume-changeable pressing filtering space used for containing materials is arranged between the adjacent filtering plate sets. Each filtering plate set is provided with a material channel which is communicated with the pressing filtering space. The other side of the main plate, opposite to the contact face of the auxiliary plate, is provided with a filtering mesh. Filter cloth wraps outside the filtering mesh. Each filtering plate set is also provided with a gas channel and a liquid channel which are communicated with the outside to the pressing filtering space. The pressure filter is high in structure reliability, has no leakage of the materials, and is convenient to maintain. The invention further provides a pressing filtering method. As pressing filtering and drying above the third level are adopted, water-filtering effect is better, size of the pressed and filtered material is larger, water containing rate of the materials is lower, work efficiency is higher, and production is higher.