The utility model relates to a water level measurement device for a starting deaerator, which comprises a water level measuring barrel (1) and a liquid level transmitter (2), wherein the water level measuring barrel (1) consists of a first balance container (11) and a second balance container (12); the upper part of the first balance container (11) is communicated with an air communication pipe (31) at the upper part of the starting deaerator (3), and the bottom end thereof is connected with the liquid level transmitter (2) through a positive pressure side pipeline (11-1); and the side wall of the second balance container (12) is communicated with the water communication pipe (32) at the lower part of the starting deaerator (3), and the bottom end thereof is connected with the liquid level transmitter (2) through a negative pressure side pipeline (12-1). The water level measurement device for the starting deaerator is characterized in that a water replenishing pipe (4) is arranged on the positive pressure side pipeline (11-1), the water inlet of the water replenishing pipe (4) is communicated with a condensate pump outlet drain pipe (5), and a stop valve (41) is arranged on the water replenishing pipe (4). The water level measurement device for the starting deaerator overcomes the defect of insufficient deaerating of condensed water, avoids the oxidized corrosion on a waste heat boiler, and ensures the safe operation of the waste heat boiler.