Abstract: Taking the construction project of a large diameter (8.8 meter) shield advancing through an existing tunnel constructed by mining method in the southeast coastal area as subject, the construction control measures and deformation control technology during periods of before entering the tunnel, advancing without load and exiting the tunnel are studied. Results show that after construction, the segment installation of the mined tunnel that is crossed without load has maximum deviation of 11 mm and 9.6 mm in left line level and elevation respectively. The maximum deviation is 12 mm and 10 mm in right line level and elevation respectively. The maximum settlement amount of the tunnel roof is 2.42 mm in the left line and is 4.61 mm in the right line. The segment installation deviation and tunnel settlement both meet the control standards of the specification, and it is guaranteed that large diameter shield machine can pass through the hard rock section quickly, safely, with high quality. Not only the time until completion is saved, but also can it ensure quality and safety of tunnel construction.