An analytical method for flavones of Astragalus has been developed and a process of high performance liquid chromatographic (HPLC) condition optimization has been elaborated. The LC retention parameters of 34 components were obtained quickly by using three linear gradient elutions. Overlapping separation range map (OSRM), which is related to the separation quality and the analysis time, was utilized to search the optimised stepwise gradient method for HPLC analysis of flavones of Astragalus. Finally, the optimised stepwise gradient elution conditions were set up with the help of this map. Under the optimised conditions, the sample of flavones of Astragalus was well separated in reasonable time. The method is more convenient than that using a series of isocratic elutions.