A mounting assembly is used to fix a toilet on a toilet flange and contains two L-shaped brackets fixed on the toilet flange and each having a horizontal portion and a vertical portion. The horizontal portion has an internally raised portion, an externally raised portion, and a locating groove. The internally raised portion is retained in each arcuate slot of the toilet flange, and the locating groove is horizontally formed on the peripheral fence. The horizontal portion further has a recess for inserting an extension of the second bolt, so that the extension screws with a nut. The vertical portion has a plurality of openings defined thereon, so that the first bolt inserts into the through hole of each longitudinal fence to screw with one of the plurality of openings, such that the toilet is positioned on the toilet flange by ways of the mounting assembly.