Abstract: Titanium silicalite-1(TS-1) molecular sieves with different Si/Ti were hydrothermally synthesized with tetraethyl orthosilicate as Si source, tetrabutyl titanate as Ti source and tetrapropyl ammonium hydroxide as template and modified with organic base. The structure and morphology of TS-1 sieves were characterized by XRD, UV-Vis, FI-IR and SEM. The Si-Ti sieves prepared are proved to have the typical MFI structure. At Ti/Si of 70(TS-1-70), no non-framework anatase is observed. It is found that after treatment with propyl ammonium hydroxide for TS-1-70, hierarchical pores with 2-6 nm meso-pores appear with broad pore size distribution, while still retaining the original MFI topology. The propylene epoxidation with modified TS-1-70 was conducted in a continuous slurry bed reactor. Under the optimal conditions, the catalyst can steadily run for over 160 h with high activity, demonstrating the good stability of the modified catalyst.