The invention discloses a construction method of a double arch tunnel auxiliary middle wall without a middle
pilot tunnel. According to the technical points, firstly, an upper step of a left side tunnel is constructed, then a primary support is constructed, and a lower step of the left side tunnel is excavated; the auxiliary middle wall is conducted, specifically, a vertical
steel frame is constructed in the corresponding position of an inverted arch, after concrete of the inverted arch is constructed, an inclined strut on the right side of the
steel frame is constructed, and a horizontal transverse-strut
steel frame is constructed; rebars are fixed on the steel frame in a quincuncial mode; meanwhile, double
layers of reinforcement fabrics are hung on the horizontal transverse-strut steel frame; then sprayed concrete is constructed on the steel frame, and a secondary lining of the left side tunnel is constructed on the left side of the concrete; and a right side tunnel is constructed, specifically, an upper step is excavated, then a primary support is constructed, a middle step is excavated, a primary support of the middle step is constructed, a lower step is excavated, the primary support and the inclined strut on the right side of the middle wall are dismantled, an inverted arch of the right side tunnel is constructed, and finally a secondary lining of the right side tunnel is constructed . Middle
pilot tunnel construction is omitted, the construction safety of a main tunnel is guaranteed, an existing construction method is fully utilized, construction efficiency is improved, and the construction period is shortened.