A new method for life- time measurement using two- photon storage is suggested. By delaying the time interval between shutting preexciting-beam and opening writing-beam and analysing the variation of efficiencies, we obtain the life- time of relavent energy level. The metastable life-time 4s and 2. 7 s of methyl orange (MO) and ethyl orange (EO) are obtained with this method.