Waste heat boiler drum liquid level control system

The invention relates to a waste heat boiler drum liquid level control system. A water supply pipe (21) and a water drainage pipe (22) are each provided with an adjusting valve (23) and a circulating pump (24). A floating plate (25) which ascends and descends along with the liquid level is arranged in the steam pocket (10), and a control rod (26) is fixedly arranged on the floating plate (25); when the liquid level of the steam drum (10) gradually rises to a high water level, the floating plate (25) drives the control rod (26) to move upwards so as to control the regulating valve (23) on the drain pipe (22) to be opened and drain water through the circulating pump (24), so that water supply and drainage actions are automatically performed according to the change of the liquid level in the steam drum (10), the liquid level in the steam drum (10) is always kept between the low water level and the high water level, the liquid level is prevented from being too low or too high, and the safety of the steam drum (10