The filter is composed of a cylinder, a filter screen, a blowdown part, a transmission device and an electrical control part. After the water to be treated passes through the filter drum of the filter screen, its impurities are blocked. When it needs to be cleaned, as long as the detachable filter drum is taken out, it can be reloaded after treatment. Therefore, it is very convenient to use and maintain. According to the filter material or the different operation requirements, the form of specifications up to dozens of.