Precise filtering device for injection and filtering method thereof

The invention relates to a precise filtering device for injection. The filtering device comprises a filter, the filter comprises a main filter body, a valve element, a filter upper cover and a rotaryknob for rotating the valve element, and the main filter body is provided with an element groove which provides convenience for installation and rotation of the valve element; the element groove is provided with three or more ports matched with an injector or an injection needle in the circumference direction, and one or more ports are provided with filtering membranes for filtering a medicine solution; a liquid channel is formed in the valve element, and the liquid channel is provided with multiple circulation ports used for being communicated with any two ports at a time. The device is reasonable in design, convenient to use and safer to nurses and patients, particle pollution in the medicine solution is avoided as much as possible, and the patients are prevented from being harmed by particle pollution; convenie