In this study, we present a new method to compute internal co-seismic deformations of a homogeneous sphere, based on our previous approach(Dong et al.2016). In practical numerical computations, we consider a strike-slip point source as an example, and compute the vertical co-seismic displacement on different internal spherical surfaces(including the Earth surface). Numerical results show that the internal co-seismic deformations are generally larger than that on the Earth surface; especially,the maximum co-seismic displacement appears around the seismic source. The co-seismic displacements are opposite in sign for the areas over and beneath the position of the seismic source. The results also indicate that the curvature effect of the internal deformation is pretty large, and larger than that on the Earth surface. The results indicate that the dislocation theory for a sphere is necessary in computing internal co-seismic deformations. In this study, we present a new method to compute internal co-seismic deformations of a homogeneous sphere, based on our previous approach (Dong et al. 2016). In practical numerical computations, we consider a strike-slip point source as an example , and compute the vertical co-seismic displacement on different internal spherical surfaces (including the Earth surface). Numerical results show that the internal co-seismic deformations are generally larger than that on the Earth surface; especially, the maximum co-seismic displacement appears The co-seismic displacements are opposite in sign for the areas over and beneath the position of the seismic source. The results also indicate that the curvature effect of the internal deformation is pretty large, and larger than that on the earth The results indicate that the dislocation theory for a sphere is necessary in computing internal co-seismic deformations.