Abstract: The SAPO-11 seed crystal was first silylanized using n-Propyltriethoxysilane (Pr-TES) in synthesis process and the SAPO-11 molecular sieve with small particle size (H-SAPO-11-S) was then synthesized by crystallization in cyclohexane-1-butanol system. Samples were analyzed by XRD，SEM，nitrogen adsorption-desorption and Py-IR. Characterization results show that pure phase SAPO-11 molecular sieve is obtained by silylanizing seed crystal. The mean particle size for H-SAPO-11-S molecular sieve is much smaller than normal SAPO-11 molecular sieve (H-SAPO-11-N) synthesized by conventional method, reducing from 8.0 μm of H-SAPO-11-N to 1.0 μm of H-SAPO-11-S. Compared with H-SAPO-11-N molecular sieve，H-SAPO-11-S molecular sieve possesses much more external specific surface area, larger pore volume and more suitable acid amount and acid strength. The results of n-hexadecane hydroisomerization show that the catalyst Pt/H-SAPO-11-S exhibits much better activity and higher isomers selectivity than that of the Pt/H-SAPO-11-N catalyst.