The multi-bag filter adopts the side-in and bottom-out method (bottom-in and bottom-out method can also be adopted). The filter liquid medium is pressed or pumped into the filter barrel through the pressure in the pipeline. The liquid medium to be filtered is filtered through the filter bag supported by the electro-polished punching support filter basket, producing an ideal solid-liquid separation to achieve the effect of filtering the liquid medium. It has the characteristics of high throughput, repeated flushing, long life, excellent filtration accuracy, and low economic cost, and is particularly suitable for pre-filtration and clean filtration.