Abstract: In view of the rebound phenomenon in numerical simulation calculation of rock & soil excavation, based on the M-C elastic-plastic constitutive model, the rebound effect is studied during the excavation process of a foundation pit. The mechanical mechanism and the sensitivity of the mechanical parameters for the rebound effect in rock mass constitutive model are analyzed. Besides, the solution to the rebound in numerical simulation of excavation is explored. The research results show that the effect of parameters in the M-C constitutive model on the rebound is as follows: (1) The impact of geotechnical gravity density on rebound of general rock mass excavation is relatively sensitive, and the effect on the bottom is far more significant than that on the surface. (2) The effect of Poisson's ratio on rebound displacement of excavating rock & soil is also obvious. (3) When the ratio of reduction is small, the sensitivity of elastic modulus and cohesive force is prominent. The effect on the bottom and the surface is significant on the whole. (4) However, the internal friction angle of rock and soil basically has no effect on the bound deformation. This study may provide reference for the design of excavation of foundation pits and rebound prediction.