A projection device comprises first light sources, an interference disk, a condensing lampshade, and a driving device. Both of the interference disk and the condensing lampshade are arranged on light paths of the first light sources. The condensing lampshade is arranged behind the interference disk, and the interference disk is made stationary relative to the first light sources. The driving device drives the condensing lampshade to rotate. When the driving device drives the condensing lampshade to rotate, the projection light emitted after sequentially passing through the interference disk and the condensing lampshade projects an effect of clouds moving. The light paths of the projection light emitted by the first light sources are relatively stable after passing through the interference disk and before entering the condensing lampshade.