A fixing buckle assembly of a slide rail used for an industrial cabinet includes a fixing frame, a plurality of fixing members, a fixing plate, a hook plate, and an elastic member. The fixing frame is mounted to an end portion of the slide rail and is reversely bent to form a mounting surface corresponding to a surface of the slide rail and has a notch adjacent to the mounting surface. The hook plate and the elastic member are sandwiched between the mounting surface and a slide space formed by the fixing plate through the fixing members. When mounted to the industrial cabinet, the two protruding posts of the fixing plate are inserted in two of buckle holes of a rack, and the hook plate is driven by the elastic member to be engaged with a back of the rack to be in a locked state.