The invention relates to the field of water treatment, in particular to a filter capable of preventing a filter screen from being blocked. The filter is composed of a control box, a drive device, a sewage cavity, a clean water cavity, a filter core, an electro-catalysis treatment device, and an electro-catalysis dedicated power supply. The electro-catalysis treatment device is arranged in the sewage cavity. The electro-catalysis dedicated power supply is arranged in the control box. The filter capable of preventing the filter screen from being blocked can generate hydroxyl radicals capable of oxidizing organic matters greatly in water in cavities in the utilization process, and the hydroxyl radicals can effectively oxidize organic matters in living bodies in water, so that the living bodies in water are killed or protection layers of the living bodies in water are destroyed. Consequently, the purpose that bionts are killed or restricted is achieved, and water bionts are effectively restricted from growing and are prevented from adhering to the filter core. The backwash effect of working of the filter is effectively improved, the filter is prevented from being blocked, and eventually the filter screen is prevented from being blocked.