The invention relates to the technical field of backlight modules, in particular to a backlight plastic-iron assembly and a preparation method of the backlight plastic-iron assembly. The backlight plastic-iron assembly comprises an iron frame and a plastic frame which are integrally formed. The plastic frame is made of a plastic mixture. The plastic mixture is made of plastic and nano-scale metaltin. Since the iron frame and the plastic frame are formed at the same time, the connection strength between the iron frame and the plastic frame in the backlight plastic-iron assembly is good. Compared with the prior art, the preparation method of the backlight plastic-iron assembly has the advantages that since the iron frame and the plastic frame are formed at the same time, the connection strength between the iron frame and the plastic frame in the backlight plastic-iron assembly is good; in addition, since the rubber frame is formed through injection molding of the plastic mixture, and the plastic mixture is made of the plastic and the nano-scale metal tin, the physical properties of the plastic frame and the iron frame in the prepared backlight plastic-iron assembly are approximate,and the connection strength between the iron frame and the plastic frame can be further improved.