The invention relates to a volute tongue structure of a fan for a range hood. An inner concave surface is formed on one side, facing an air outlet of the fan, of a volute tongue. The volute tongue structure is characterized in that the volute tongue comprises a front disk, a central disk and a rear disk, wherein the side parts, facing to the air outlet of the fan, of the front disk, the central disk and the rear disk wholly form the inner concave surface, the front disk further extends to the bottom left to form a front side deep tongue on the basis of the inner concave surface, the rear disk further extends to the bottom left to form a rear side deep tongue on the basis of the inner concave surface, and the central disk is continuously and inwards concave to form a central short tongue on the basis of the inner concave surface. Compared with the prior art, the volute tongue structure disclosed by the invention has the advantages that the volute tongue forms the front side deep tongue, the rear side deep tongue and the central short tongue, the gap between the front disk, the rear disk and a vane wheel is smaller, and the gap between the central disk and the vane wheel is larger, so that the speed at which front and back air currents flow out cannot be much lower than the speed at which the central air current flows out, the whirlpool caused by a low speed of two sides and high speed of the center is eliminated, and further the whole efficiency of the fan is improved.