The enhancement of total X-ray emission from nano-porous Au targets under double laser pulses irradiation is reported. Total X-ray yield is calculated in the soft X-ray wavelength region (0.1–10nm). The effects of different delay times and intensities are investigated to reach optimum conditions. Significant enhancement can be obtained by choosing optimum values for delay time and the prepulse intensity. About 3.5-fold enhancement was obtained for a porous Au target with density ratio 1/2 at optimum conditions.