In order to solve the problems of long setting time, low early strength and poor impermeability of ordinary sprayed concrete, the performance of ordinary sprayed concrete was improved by adding nano-C-S-H (Calcium Silicate-Hydrate) material. Taking setting time, mechanical properties and impermeability as macro indicators, and with the help of micro technologies such as hydration heat test, XRD(X-ray diffraction) and SEM(Scanning electron microscope), the influence of nano-C-S-H materials on the hydration law and micro-morphology of sprayed concrete was explored. The results show that nano-C-S-H gel can obviously shorten the setting time of cement paste mixed with accelerator. Compared with the reference group, the 1-day compressive strength of sprayed concrete mixed with 2% nano-C-S-H gel can be increased by 19.0% and the water seepage depth can be reduced by 31.4%. The mechanism analysis shows that the crystal nucleus and filling effect of nano-C-S-H material can promote the hydration of cement and improve the internal structure of concrete, thus improving the properties of sprayed concrete.