Abstract: The experiment and data reduction techniques were improved in the self-consistent method (so called AC method). One-stepped sample and single-flyer instead of the usual two-stepped sample and two-layer combined flyer were used in loading-unloading experiments. This experimental configuration can meet the physical requirements and simplify the wave interaction of loading-unloading process. The location of elastic-plastic transition is more accurately identified based on the acquired Lagrangian sound velocity against particle velocity, relative to based on the Lagrangian sound velocity against engineering strain. The dynamic yield strength of LY12-aluminum treated by low temperature annealing at 20.0 GPa shock stress was measured by using the improved AC method. The results obtained by integral method and graphical method are consistent.