Based on the geological condition, environmental condition, and the depth of excavation, by comparison and demonstration on the schemes, the design of one ‘deep foundation pit’ was changed into tow ‘shallow foundation pits’. The upper foundation pit was constructed with the composite support plan; the lower part was supported with bored grouting pile and an annular horizontal inner bracing reinforcement with concrete. This optimal combination of multiple support techniques was proved safe and economical, could be the reference to the similar design of ultra 100m depth excavations in the same area.