The utility model relates to a venturi tube injection device for fine particulate matters. The injection device is mainly used for sending the fine particulate matters to a reactor in a settling furnace, and the injection device adopts the structure as follows: air inlet pipelines are symmetrically and circumferentially arranged at the upper part of a venturi tube, and a fine particulate matter dropping pipe extends into the throat of the venturi tube from the upper part. The injection device has the advantages that uniform air flows in the circumference direction are accelerated when passing through the throat of the venture tube, air flow disturbance caused by the larger temperature difference at an operating inlet of the reactor of the settling furnace is overcome, and the fine particulate matters required to be sent into the reactor of the settling furnace are limited to flow in the axis direction, so that the one-dimensional property of movement of the fine particulate matters in the settling furnace is guaranteed, and the operating accuracy of the settling furnace is improved.