Abstract: The effects of pH value of liquid feed as well as the presence of monomethyl ether (MME), ethyl thiol and rust in the feed on the catalytic performance of TS-1 in propene epoxidation were investigated, where the epoxidation was carried out in a continuous fixed-bed reactor and gaseous propene was pre-mixed with dilute solution of hydrogen peroxide in methanol. It was shown that the presence of MME in feed has no impact on the catalytic performance of TS-1. The addition of ethyl thiol in the feed exhibits little effect on the catalytic activity, but may cause a decrease in propylene oxide (PO) selectivity. The pH value of liquid feed influences the catalytic performance significantly; an optimum pH value is about 7. The rust in the feed may block the pores of TS-1 and then cause a partial deactivation. With a liquid feed pH value of 7 (adjusted with 0.1mol/L ammonia water), the catalyst TS-1 exhibits excellent stability at 55℃ and 0.7MPa; both H2O2 conversion and PO selectivity exceeded 90% in a 130h catalytic test.