The ferrisilicate molecular sieve analogue of the ZSM-5 was prepared from the weak alkaline medium(pH 8) in the presence of F^- ions, which was confirmed by IR, X-ray powder diffraction, EPR, and ²⁹Si MAS NMR studies. The addition of F^-ion in the preparation of metallosilicate molecular sieves could reduced the pH value of the reacion mixture, and prevent from the precipitation of metal ions which are sparingly soluble in strong alkaline media.