The lifetime of Er3+ and 4I13/2 energy level is of very significance for evaluating the application potential of Er3+-doped materials in optical communication. In the present article, based on the Er3+ excited state absorption upconversion (UC) luminescence under 980 nm double-pulse injection LD excitation, the authors detected the red UC luminescence intensity under different time gap between double pulses, then according to the dependence between UC red luminescence intensity and time gap between double pulses, deduced the fitting formula for obtained medial energy level lifetime of Er3+, and actualized the measurement of infrared level lifetime in visible region. So, combining photomultiplier tube (R2658) with double-pulse injection LD module with controllable time gap and synchronous pulse sample, we can obtain all the infrared level lifetime of Er3+, and this is a cost saving lifetime measurement system with μs resolution.