Abstract: SAPO-11 zeolites were hydrothermally synthesized with n-dipropylamine(DPA) as template. The effects of nature of silica sources, ratios of raw materials and crystallization parameters such as crystallization temperature，time and pH value, on SAPO-11 crystallization were systematically discussed. Of interest is that the nature of silicon feed was justified to be one of key factors for synthesis of SAPO-11 zeolites. The selective tests of Si resources proved that acidic silica gel is a suitable feed, which could provide active silica intermediates just accompanying by slow formation of SAPO-11 precursor. It was shown that highly crystalline SAPO-11 zeolites could be produced with material ratios of SiO2/Al2O3=0～0.7，DPA/P2O5=0.8～1.8 and under contiguously neutral media environment (pH=5.8～7.8). In addition, it was found that SAPO-11 zeolite appeared after 4 h and completely crystallized after 24 h, following by transformation between SAPO-11 and 31 with time on.