The design values of swelling force in the construction of deep foundation pits have not been decided in China’s current technical specifications. In this paper, the comparison between design results of internal force of foundation pit of Phase 1 on Chengdu Metro Line No. 3 and site monitoring results is made in terms of different swelling force design values. The relationship between monitoring results and theoretical calculation results is studied. The study resalts can provide guidance for design values of swelling force in construction of deep foundation of similar projects in the future.