Provided are a compound represented by formula I, a raceme thereof, an R-isomer thereof, an S-isomer thereof, a pharmaceutical salt thereof, and a mixture thereof, a preparation method therefor, a pharmaceutical composition comprising the compound, and uses thereof serving as an lysine specific demethylase 1 (LSD1) inhibitor. Provided are uses of the fluorinated cyclopropylamine compound represented by formula I in the treatment of cancers.