The impermeability mechanism of water-proof self-compacting concrete (WPSCC )w as studied. The mechanism and influential factors, such as water-cement ratio(w /c), dosage of powder, superplasticizer, sand content, aggregate conte nt, fly ash, UEA, PP fiber, on compactibility and crack resistance of WPSCC were analyzed. A type of WPSCC successfully applied in tunnel liner with its validit ies, conveniences and economies by mockup test was developed and optimized. Expe rimental results show that the WPSCC has good workability, mechanical properties and impermeability when reasonable requirements are fulfilled. The impermeability mechanism of water-proof self-compacting concrete (WPSCC) w as studied. The mechanism and influential factors, such as water-cement ratio (w / c), dosage of powder, superplasticizer, sand content, ash, UEA, PP fiber, on compactibility and crack resistance of WPSCC successfully applied in tunnel liner with its validities, conveniences and economies by mockup test was developed and optimized. Expe rimental results show that the WPSCC has good workability, mechanical properties and impermeability when reasonable requirements are fulfilled.