In the highly permeable soil, pure bentonite slurry is hard to form a filter cake at the tunnel face during slurry shield tunnelling. The viscosity of polymer modified slurry is too high and it may pollute the environment. The enhancement mechanism of biomass straw fiber on the filter cake formation for bentonkte slurry during slurry shield tunnelling in saturated sandy soil was introduced. The infiltration process of slurry in saturated sandy soil was investigated using column infiltration test. The filtration loss, filter cake formation and effective pressure transfer were analysed. The effects of biomass fiber content on filter cake formation and effective pressure transfer were discussed. The results show that: (1) the viscosity of biomass fibre enhanced slurry is low, the stability of suspended particles is high and the density of biomass fibre enhanced slurry is low; (2) the ability to form a filter cake of the biomass fibre enhanced slurry is greatly improved, which can reduce the use of bentonite; (3) the infiltration model well predicts the infiltration process of biomass fiber enhanced slurry.