Superfine powder grading device and method thereof for grading superfine powder

The invention discloses a superfine powder grading device, comprising a grading main device, a container, a filter screen, a pump and a liquid storage tank. The grading main device comprises a charging pipeline, a horizontal pipeline and a discharging pipeline, which are connected in order; the container is located below a liquid outlet of a discharging bent pipe of the discharging pipeline; the filter screen is horizontally arranged in the container; a liquid inlet of the pump is connected with a liquid outlet of the container through a pipeline while a liquid outlet thereof is communicated with the liquid storage tank through a liquid transportation pipe; a liquid outlet of the liquid transportation pipe is located above the liquid storage tank; and a liquid outlet of the liquid storage tank is communicated with the upper end of a charging vertical pipe of the charging pipeline. The method for grading the superfine powder by using the superfine powder grading device has apparent grading effect.