The invention discloses an indoor air ventilation device based on the Coanda Effect. The indoor air ventilation device comprises a Coanda airfoil-shaped panel, an arc-shaped shield plate, a bottom plate, side plates, an air inlet barrel, an annular frame and a variable frequency fan, wherein the Coanda airfoil-shaped panel, the arc-shaped shield plate and the side plates are arranged on the bottom plate; the arc-shaped shield plate is arranged on the upper end, on which a flow guidance head provided with a smooth curve surface is arranged, of the Coanda airfoil-shaped panel; the two side plates are separately arranged on the two sides of the Coanda airfoil-shaped panel and the arc-shaped shield plate; an air inlet cavity is formed by the Coanda airfoil-shaped panel, the arc-shaped shield plate, the side plates and the bottom plate; a strip-shaped air outlet is formed between the arc-shaped flow guidance head of the Coanda airfoil-shaped panel and the arc-shaped shield plate; the air inlet barrel is arranged on the bottom plate, and is communicated with the air inlet cavity; the assembly height of the air inlet barrel is lower than that of the strip-shaped air outlet, so that noise which is generated when air flow flows out of the air inlet cavity is reduced; the annular frame is arranged in a barrel hole at one end of the air inlet barrel; and the variable frequency fan is arranged in the barrel hole of the air inlet barrel, and is fixed on the annular frame through screws.