A hydroponic circulation liquid supply device is composed of a tray body, a liquid supply platform and a motor. The tray body has a containing space for disposing a liquid supply platform. The liquid supply platform is formed with a liquid supply region and a guide passage region communicating with each other by disposing a first rib. The liquid supply region is disposed with a plurality of second ribs to form a liquid supply passage. A water collection region is further disposed in the tray body. The liquid supply region and the guide passage region have a section difference plane. The motor is engaged with the water collection region and the liquid supply region respectively to form a flowing circulation loop of transporting culture liquid, and the flowing speed of culture liquid can be slowed down.
