Engineering cementitious composites (ECC) have excellent toughness and crack control ability, which can be used in underground and hydraulic engineering solving the problems of concrete cracking and leakage. ECC with high water-cement ratio (w/c=1.03) has excellent fluidity, but its impermeability is poor. Meanwhile, the high water-cement ratio also induces large slump and poor cohesiveness, leading poor sprayable abilities. In order to solve the above problems, silica fume (SF) was then introduced into ECC (w/c=1.03) with different SF/cement mass ratios to improve its workability, impermeability, microstructure and mechanical behavior. The results indicate that when SF/cement ratio was 15%, the workability of ECC with high water-cement ratio was greatly improved, which could be pumped and sprayed. At the same time, the impermeability of ECC with high water-cement ratio is improved to above P8. The scanning electron microscope （SEM） and energy dispersive spectrometer (EDS) observations confirmed that adding SF made ECC microstructures denser, but also could reduce the alkaline substances to inhibit alkali-aggregate reaction and improve durability. Through the study of toughness, impermeability and workability (pumpable and sprayable) of ECC, the mix proportion of ECC with high toughness, high impermeability, spraying and pumping was obtained, which laid a foundation for the popularization and application in practical engineering.