The dispersion degree of glass fiber in concrete is related to the mechanical properties and impermeability of glass fiber concrete. In this paper, the effects of polymer type hyperdispersant (B193), polyether modified polymer (S-3101B) and sodium carboxymethyl cellulose (CMC) on the microstructure, surface condition, compressive strength, splitting tensile strength and impermeability of glass fiber concrete were investigated. The results show that the three dispersants improve the dispersivity of glass fiber in glass fiber concrete, but the dispersant S-3101B mixed into the concrete causes many pores in the concrete, which reduces the mechanical properties and impermeability of glass fiber concrete. When the dispersant B193 dosage is 0.5% (mass fraction relative to the gel material, the same below), the best impermeability of glass fiber concrete specimens is achieved, and the seepage height is reduced by 16.6%. When the dosage of dispersant CMC is 0.5%, the seepage height is reduced by 7.1%. The relationship curves between seepage height and dispersant dosage of glass fiber concrete mixed with three dispersants are established for engineering design reference.