A decorative device enabling ornaments to revolve on a rotary screen inside a crystal ball amidst fluttering, shiny disc snowflakes, which uses a device structured from a motor mechanism, a gear mechanism, a rotary screen mechanism and a crystal ball so that when a motor drives and rotates transmission gears of the gear mechanism, apart from using mutually repelling of two double-sided magnets to drive and rotate a magnet impeller wheel, and thereby cause whirling of water and fluttering of shiny disc snowflakes within the crystal ball, moreover, a main transmission shaft is also driven, thereby driving and causing a PVC (polyvinyl chloride) rotary screen to revolve.