The invention relates to a lightweight dust removal device based on a rotational flow field. The lightweight dust removal device is characterized by comprising a dust collecting room (4); the middle of the bottom part of the dust collecting room (4) is interconnected with a dust collecting barrel (1) through a dust collecting pipeline (3), wherein the dust collecting room (4) is a hollow columnar shell, and at least three air inlet pipes interconnected to the inner part of the dust collecting room (4) are arranged on the outside wall of the dust collecting room (4) along the peripheral direction, and the included angle between every air inlet pipe and the outside of the dust collecting room (4) is an acute angle. The invention has the following beneficial effects, 1) the device gathers dust-containing gas flow to a circular dust collecting room at certain flow rate and dynamic pressure, and forms a high-speed rotational flow field under the effect of air flow of an air inlet; the extreme lightweight and extremely small grain diameter dust removal can be realized by using a center speed zero zone formed by the rotational flow field; 2) the device applies a second-grade dust removal structure, the dust collecting room is the primary dust removal, and a funnel mechanism is a second-grade dust removal; therefore, the dust removal effect is improved.