The bag filter is a pressure filter device, which mainly consists of a filter cylinder body, a filter cylinder cover, a quick-opening mechanism, a stainless steel filter bag reinforcing mesh and other main components. The filtrate flows into the filter bag from the side inlet pipe of the filter casing. The filter bag itself is installed in the reinforced mesh basket, and the liquid can obtain qualified filtrate by infiltrating the filter bag of the required fineness grade, and the impurity particles are intercepted by the filter bag. The machine is very convenient to replace the filter bag, and there is basically no material consumption for filtration.