Abstract: A motor-driven transmission mechanism including a motor having a drive gear coupled to an output shaft thereof and extended out of a hole on a slide way above a table, a first transmission block driven by the drive gear to move in the slide way back and forth alternatively, a second transmission block carried on the first transmission block, a cover covered on the table over the first and second transmission blocks, a transmission shaft having one end coupled to a set of transmission gears being meshed with parallel racks on the second transmission block and an opposite end extended out of the cover and coupled to an ornament, whereby turning the motor causes the transmission shaft to rotate the ornament back and forth alternatively.