Sr-doped single crystals (C1-xSx)12A7:e(-) (x = 0, 0.01, 0.02, 0.03) were successfully fabricated by floating zone method. It is found that Sr-doping decreases the reduction time from 30 h to 20 h. The maximum emission current of (C1-xSx)12A7:e(-) is greatly improved by 50% than that of the un-doped. The DFT calculations show Sr-doping in C12A7 contributed to the free O2- in the cages spread out, leading to a short reduction time; increase the "window" between two adjacent cages that is conducive to the electrons in cages to escape. And the work function of the (C1-xSx)12A7:e(-) is lower than that of C12A7:e(-).