The present invention provides a liquid level control system and method. The present invention achieves a uniformly soaking process of a substrate during different segments of a fixed time period, by using a liquid removal device to gradually remove a processing liquid from a tank. The substrate is disposed in the liquid in the tank to be wet processed. By the removal of the liquid from the tank via the liquid removal device, an area of the portion of the substrate being processed by the liquid can be gradually decreased whereby the substrate can be uniformly processed.