Abstract: Karst for the engineering construction is a very big hidden trouble.This paper introduces the principle and working method of the cross-well seismic tomographic imaging,and then briefly introduced the seismic inversion theory foundation.Finally,by using tomography inversion software in the work area to get original data inversion processing,get different line of inversion profile to explain.Through the project example application result shows that crosswell seismic CT technology in karst exploration has higher precision and reliability,for engineering design and provides the reliable basis.