The present paper analyzes the different pump wave theory under the fluorescence decay law, and presents a different pump wave measured fluorescence lifetime of the new method—double-pulse detection method, namely the use of pump pulse and probe pulse for the fluorescence decay methods to measure fluorescence lifetime. By measuring the sample neodymium glass and Cr∶ZnSe crystal fluorescence lifetime, results showed that: using this method can be achieved under different pump wave in visible and near-infrared to the mid-infrared laser medium of the fluorescence lifetime measurement. Therefore, using the measurement method can be convenient and effective to avoid seeking samples by deconvolution for fluorescence lifetime with the cumbersome process of measuring laser medium at different pump wave under the fluorescence lifetime with a reference value.