Based on Xi'an Metro #2 interval tunnel through the south gate of the ancient city wall

three possible construction programs by the establishment of FLAC3D numerical model are accomplished. The program is suggested that is formed by segment support and grouting behind the segment

chemical grouting in the soil within the city gate and piling bored piles closed to the ancient city wall south foundation as the best joint construction program. The deformation law of the ancient city wall caused by the joint program is studied; and the monitoring program is given. It is shown that the method suggested of deformation control technique for the ancient city wall is reasonable; and the deformation of the ancient city wall and the surface caused by metro shield tunneling is in the safe range. Deformation law is obtained from the ancient city wall caused by the metro shield tunneling and its control technology. The experience are beneficial to the Xi'an Metro #1 which will be through the east and west ancient city wall.