Based on the engineering case of the pit in the pit of Nanchang aixihu tunnel，the deformation characteristics of the pit (including the influence range of surface settlement, the maximum surface settlement and the maximum horizontal displacement of the retaining structure) under different spatial forms of the pit (including the size, relative position and the insertion ratio of the retaining structure) are studied and analyzed by using the numerical calculation software. And the influence rate of foundation pit deformation is proposed, which can be used to comprehensively judge the sensitivity of pit spatial shape parameters to foundation pit deformation.The results show that the influence factors of the spatial form characteristics of the deformation characteristics of the pit in pit are mainly the relative size, relative position of the inner and outer pits and the insertion ratio of the enclosure structure. The specific sensitivity relationship is: relative depth > relative position > insertion ratio of the outer pit enclosure structure > insertion ratio of the inner pit enclosure structure > relative width.