The invention relates to a foldable blade vertical axis impeller based on connecting rod transmission. The foldable blade vertical axis impeller comprises a bearing pedestal, a main shaft, an upper blade support, a lower blade support, four gear sets, four blocking rods, four outer blades, four inner blades and two connecting rod transmission mechanisms. The positions of the blades can be changed through regular rotation when the foldable blade vertical axis impeller rotates around the axis; the blades can be unfolded to form a flat plate when facing the wind, the windward area is enlarged, and the borne rotation torque is increased; the blades can be folded when against the wind, the headwind resistance is reduced, and the draught fan impeller has the good self-starting performance and has the high power generation efficiency as well.