Harmful gas protection device for tunnel construction

The utility model belongs to the technical field of tunnel construction, and particularly relates to a tunnel construction harmful gas protection device which comprises a tunnel body. A first air pipe and a first water pipe are mounted in the tunnel body through fixing modules; the first air pipe and the first water pipe are arranged adjacently; a plurality of air outlets are formed in the middle of the first air pipe; the multiple air outlets are distributed at equal intervals in the length direction of the first air pipe. The end parts of the plurality of air outlets are fixedly connected with conical openings; by means of the structure, the interior of the tunnel body can be treated through gas and liquid at the same time, harmful gas in the tunnel body is diluted by healthy gas sprayed out of the conical opening, and therefore the harmful gas in the tunnel body can be purified. And meanwhile, a part of harmful gas capable of being dissolved in water can be dissolved by liquid sprayed out of the first wate