Ti-MCM-41 catalyst was silylated with a new silylating agent, N-trimethylsilyl-imidazole (TMSI). TMSI was found to be more effective to improve the hydrophobicity and the catalytic performance of Ti-MCM-41 than other silylating agents. Different levels of silylation were obtained by varying the silylation time. A linear relationship was observed between the degree of silylation and each of the intensity ratios I-1260/I-1083, I-845/I-1083 and I-760/I-1083 of SiMe3 spectra bands detected by FT-IR or the intensity ratio SiMe3/SiO2 of the Si-29-MAS-NMR signals. High level of silylation degree significantly enhances both the catalytic activity and the selectivity to epoxide.