A multi-layer water sealing device, includes at least two layers of water seal sequentially arranged from top to bottom. An upper-layer water seal has a floating bell-shaped cover structure, and the floating bell-shaped cover structure includes a water sealing box and a floating bell-shaped cover arranged in the water sealing box. A lower-layer water seal is arranged in a drain pipe below the floating bell-shaped cover, and one side of the water sealing box is extended to form or connected to a communication cavity offset from the drain pipe. The floating bell-shaped cover correspondingly is extended to form or connected to a floating component floatable in the communication cavity and offset from the drain pipe.