Abstract: Quasi-isentropic compression can be used to investigatedynamics characteristics of solid material in large pressure range. But, bynow, only velocity histories of sample surfaces with different thickness canbe measured directly. To obtain the inner information of the solid sample,the backward integration method is used. The traditional backwardintegration method is based on non-viscous fluid model, and is not suitablein solids experimental data processing. Several improvements on the backwardintegration method are presented in this paper: deviatonic stress iscalculated using fluid elastic-plastic model; isentrope derived fromH\"ugoniot line is used for describing thermodynamic response, and thepressure-volume relation is varied by parameters optimizing method. Usingthis improved backward integration method, experimental data of copper andaluminum samples compressed by magnetic drive and laser drive respectivelyare analyzed. The load histories and quasi-isentropic lines agree well withthe data from references.