A packaging structure for an LED lamp contains: a casing, a substrate, a printed circuit board (PCB), and at least one locking element. The casing, the PCB, and the substrate are stacked and adhered together. The at least one locking element respectively inserts into and retains with two connection gaps between the casing and the substrate so as to fix the casing and the substrate together. The substrate includes a stepped groove defined on a central portion thereof and facing the casing, and the stepped groove of the substrate has a first accommodation part and a second accommodation part. A size, a profile, and a depth of the first accommodation part correspond to a size, a profile, and a thickness of the casing. A size, a profile, and a depth of the second accommodation part correspond to a size, a profile, and a thickness of the PCB.