A radiator grille of an automobile includes a plastic main grille provided with plural air vents and plural positioning bases formed in the inside. Each of the positioning bases has a plugging groove for being inserted with a hooking member, which is made of metal with a locking portion located at one end, a blocking portion elastically extended outward, and a hunched positioning portion formed outwardly. So, with the hooking members made of metal to possess a strong strength and elasticity, they are not to be easily broken owing to improper operation while being assembled with the main grille. Moreover, the radiator grille can not only be conveniently and swiftly assembled, but also firmly positioned in a car.