Shotcreting is one of the key technologies of NATM, and it plays an important role in tunnel rock stability. Accelerator is an essential admixture in sprayed concrete, and it has a significant influence on quality of sprayed concrete. The authors present a new highly efficient accelerator, which has characteristics of small dosages, short setting time and little loss of the later strength. Volume for the general quality of cement is 1%~3%. Initial setting time is about 2 min while the final setting time is about 4 min. The loss of the later strength of the concrete is within 10%. After the actual test in tunnel engineering, the accelerator has advantages of small rebound, less dust, which is an ideal liquid accelerator for sprayed concrete, and it is worth popularizing.