Abstract: Micrometer-sized TS-1 has been modified with tetrapropylammonium hydroxide (TPAOH) solution. The effects of modification conditions, including temperature, time and concentration of TPAOH, on the catalytic properties of TS-1 in the hydroxylation of phenol and ammoxidation of methyl ethyl ketone (MEK) were investigated. The modified samples were characterized with XRD, SEM, TEM, UV-Vis and FT-IR techniques and N2 adsorption experiment. It was shown that the structure of TS-1 was basically unchanged after the modification, but etching occurred, as proved by the presence of a number of small caves in the modified samples. The optimum modification condition was as follows: TPAOH concentration of 0.15mol/L, time of 48h and temperature of 170℃. The sample modified under this condition showed a significant improvement in the catalytic performances in the hydroxylation of phenol and ammoxidation of methyl ethyl ketone.