A manufacturing method of products attached with a RFID label in a mold includes a first step of forming a thin substratum by injecting molding, pushing molding, vacuum molding, blowing molding or sword molding in a first mold, a second step of making a substratum label composed of the substratum and an RFID label adhered with the substratum, and a third step of placing the substratum label in a second mold, in which a plastic product is to be formed and also to be attached with the substratum label inside the product during molding process. The RFID cannot be broken or damaged to always maintain its capacity to be identified, with the plastic product enhanced in its value.