The invention discloses a venturi mixer with a drainage function. The venturi mixer comprises an outer pipeline, an inner pipeline and a
fuel gas inlet channel which is vertically arranged on the outer pipeline, wherein a
closed circuit chamber is formed between the outer pipeline and the inner pipeline; the inner pipeline comprises a contracting section, a
throat section and a flaring section; gas inlets are uniformly formed on one circle along the circumferential direction of the
throat section; the gas inlets are formed in an inclined form along the wall of the inner pipeline; the
fuel gas inlet channel is arranged as a gradual reducing pipeline. The
fuel gas firstly enters into the
closed circuit chamber through the fuel gas
inlet channel, and then enters into a main runner through a circle of gas inlets uniformly distributed on the
throat section, and mixes with air entering from the inlet of the main runner, so that the smooth entering of the fuel gas is ensured while the uniform gas entering along the circumference of the throat section is realized, the buffering and
pressure stabilization for the fuel gas are realized, the stable
differential pressure between the fuel gas inlet channel and the main runner is formed and the uniform stable running field of the main runner is maintained, and furthermore, the gas inlets are formed in the inclined form on the throat section, so that the fuel gas can form the confluence at a certain degree, the influence on air entering is reduced and the air flow collision loss is reduced.