Abstract: The present paper reports the systematical investigation of the influence of trace amounts of aluminium on the formation and crystal growth of M-Si-ZSM-5 type zeolites(M=B,Ga,Ti,V,Cr and Fe).It is shown that a trace of aluminium plays "nucleation-assisting" role in the formation of heteroatom-containing ZSM-5 type zeolites and accelerates the crystal growth of these zeolites by means of the comparison experiments of adding Al to the system of HMDA-Na₂O-MO_x/2-SiO₂-H₂O, electron diffraction, XPSand the calculation of the crystallization kinetic model.