The liquid-phase adsorption of acetone, butanone, cyclohexanone, 3-methylcyclohexanone and 4-butylcyclohexanone on TS-1 were measured, and the direct ammoximation reactions of these ketones with H2O2 and NH3 catalyzed by TS-1 were studied. The catalysts after reaction were characterized by TGA. The adsorption results showed that acetone, butanone, cyclohexanone and 3-methylcyclohexanone could enter into the cavity of TS-1, while 4-butylcyclohexanone could not. In the ammoximation reactions, all the ketones were converted into the corresponding oximes in high conversions and selectivities. In combination with the TGA results, it is inferred that the ammoximation reactions of acetone and butanone may occur to some extent inside the pores of TS-1. For cyclohexanone and 3-methylcyclohexanone, the ketone-involving step may occur inside the pores of TS-1 to a limited extent but for 4-butylcyclohexanone it may only occur outside the catalyst.