The present disclosure relates to a display screen assembly, an electronic device and an assembling method of the display screen assembly. The display screen assembly includes a cover plate, a display screen, a bracket and a decoration enclosure. A top surface of the display screen is joined with a lower surface of the cover plate, a width of the display screen is larger than that of the cover plate, and a side edge of the cover plate is indented inwards relative to the display screen. The bracket includes a top portion joined with a bottom surface of the display screen and a side wall. The decoration enclosure includes a first joining part joined with the side wall and a second joining part. The second joining part is joined with the side edge of the cover plate and configured to cover a non-display area of the display screen.