A candle-shape decorative lamp is disclosed, including: a aquatic lamp main body, a magnet-driven element, a buoy and a bottom base. The magnetic-driven element and the buoy are disposed inside the aquatic lamp main body. The bottom base is fixedly engaged to the conic aquatic lamp main body with at least a light-emitting element disposed inside as well as a magnetic rotational axis for correspondingly attaching to the magnet-driven element, and driven by a driving element to rotate. When the magnetic rotational axis rotates, the magnet-driven element also rotates because of attachment to the magnetic rotational axis so as to wave the fluid inside the aquatic lamp main body, which leading to pushing to rotational plats to rotate the buoy. As such, the light emitted through the aquatic lamp main body forming ambient light with decorative effect so as to great rich and fun visual effects.