The control equation of spherical cavity expansion theory of compaction grouting in saturated clay considering pressure filtration was derived to study the effect of pressure filtration on compaction grouting. Then the control equation was simplified to obtain the radial stress and radial deformation by assuming constant soil permeability, and the radial stress and radial deformation could be well calculated by simplified method. Compared with the theory in this paper, the traditional spherical cavity expansion theory can not consider the impact of effective stress ratio and pressure filtration, so that the lower effective stress ratio will lead to larger error. The results show that, with the increase of radius, the radial stress decreases notably. With the decrease of effective stress ratio, the radial stress of inner soil decreases and the radial deformation of surrounding soil increases. However, the effective stress ratio has little influence on the radial deformation of inner soil.