Disclosed is a light guide device for a water spraying device. The light guide device includes a light guide block that is a light-transmitting block having a refractive index greater than one. The light guide block has a circumferential face in which a plurality of mounting holes is defined for receiving and retaining light-emitting elements. A plurality of through holes is defined through the light guide blocks and extends in a direction substantially perpendicular to the mounting holes. Each through hole has a roughened inside surface. The through holes are in fluid communication with water discharge holes of the water spraying device so that water jets supplied from the water spraying device can flow through the through holes for discharging. The light-emitting elements emit light rays that transmit through the light guide block and get into the through holes and the water jets. The rays are subject to reflection inside the water jets to provide lighting or luminous effect to the water jets.