The invention discloses an emergency switching bypass device. The emergency switching bypass device comprises a shell, and a flue gas inlet is formed in the side wall of the shell; a first bent pipe is mounted on the side wall of the shell in a suspended manner; the first bent pipe is lower than the flue gas inlet; a first gas outlet end of the first bent pipe stretches out of the shell; a liquid accommodating tank body is arranged at the upper part of the shell; a second bent pipe is mounted on the side wall of the liquid accommodating tank body in a suspended manner; a second gas inlet end of the second bent pipe stretches out of the liquid accommodating tank body; a second gas outlet end is lower than the second gas inlet end; a flue gas outlet which communicates with the liquid accommodating tank body and the exterior is formed in the shell; the flue gas outlet stretches out of the shell; the flue gas outlet is higher than the second gas outlet end; an emptying hole is formed in the bottom of the liquid accommodating tank body; a water inlet is formed in the inner wall, outside the liquid accommodating tank body, of the shell; the emptying hole communicates with the water inlet through a pipeline; and a valve is arranged on the pipeline. According to the emergency switching bypass device, the structure is simple, the product cost is low, the response speed of switching of turning-on and turning-off states is high, the switching manner is simple and reliable, and investment is reduced.