The invention discloses a pressure release device. The pressure release device is connected with a pyrolyzing furnace and comprises: a tank body, a liquid level pipe and a pressure pipe, wherein a pressure interface and a pressure release interface are formed in the top of the tank body; the pressure interface is connected with the pyrolyzing furnace; the tank body is suitable for holding liquid;the liquid level pipe is arranged outside the tank body; the lower end of the liquid level pipe is communicated with the tank body through a first communication pipe; the upper end of the liquid levelpipe is communicated with the tank body through a second communication pipe; the pressure pipe is arranged in the tank body; one end of the pressure pipe is connected with the pressure interface; theother end of the pressure pipe extends into the liquid; in a direction from the tank body to the liquid level pipe, the end surface of the other end of the pressure pipe inclines downward. Accordingto the pressure release device disclosed by the invention, during overpressure release of the pyrolyzing furnace, an overpressure gas is discharged to the liquid from one side, away from the liquid level pipe, of the bottom end of the pressure pipe; then, fluctuation of liquid surface is relieved in pressure release, the measurement error of liquid level by the liquid level pipe is reduced, and the operation reliability of the pressure release device is improved.