The present invention provides a decoration of water lantern which mainly comprises a body, a light guide unit, and a base. The body can be filled with flow liquid inside. The light guide unit comprises a light guide plate provided inside the body, the light guide plate comprises an incident light portion contacting with the bottom of the body, and the surface of the light guide plate is provided with patterns. The base is used to fasten the body. A circuit module is provided inside the base. The circuit module is provided with at least one light-emitting diode corresponding to the incident light portion.