Abstract: A new method for anti - seepage coating of roller compacted concrete dam by using wet - mix shotcreting polyacrylate emulsion cement mortar(PAE mortar) is presented in this paper. A series of experiments are carried out for improving wet - mix shotcrete from technology and facilities to mixture of mortar. A fume - spray machine system is designed, the delivery system and the structure of spray gun are improved. The shortcoming on pipe - blocking by thick mortar and flow away of thin fluidity mortar from substrate is mitigated significantly. The improved shotcrete technique had been successfully applied in anti - seepage coating of Shanzai roller compacted concrete dam etc.