The utility model discloses a high -speed railway tunnel connects open cut tunnel with function is alleviated to micro -pressure wave, the cross -sectional area who connects the open cut tunnel is greater than the cross -sectional area in its two sections tunnels of connecting in front and back, and the cross section of just connecting the open cut tunnel is the polygon, that connects on the both sides lateral wall of open cut tunnel symmetry is provided with the vertical opening of multiunit. The utility model discloses a provide and connect open cut tunnel optimum section area, open position and cut out dimension etc. But tunnel portal micro -pressure wave is alleviated to furthest, can alleviate the helpful supplement of measure as conventional micro -pressure wave such as service gallery in tunnel import buffer structure and the tunnel to economic nature has been compromise simultaneously.