A pressure braking device, comprising: a three-pressure braking mechanism, wherein the three-pressure braking mechanism comprises a first cylinder block, and the first cylinder block has a first working chamber and a second working chamber isolated from each other; and a pressure reducing mechanism, wherein the pressure reducing mechanism comprises a cylinder block, a pressure reducing piston, a partition member, and a pressure reducing chamber, wherein a side wall of the cylinder block is provided with a working passage; the pressure reducing piston has a first end face and a second end face opposite to each other, and a side wall of the pressure reducing piston is provided with a first groove, and an area of the first end face is greater than that of the second end face; the first groove and an inner wall of the cylinder block define a piston chamber; the first end face and the inner wall of the cylinder block define a first chamber, and the second end face and the inner wall of the cylinder block define a second chamber; the cylinder block is configured to be in communication with the first cylinder block, the first chamber is configured to be in communication with the first working chamber, and the second chamber is configured to be in communication with the second working chamber; the partition member is provided in the working passage, and the partition member is configured to partition the working passage into an outside passage and a pressure reducing passage, wherein the outside passage is configured to discharge the gas to the outside; the pressure reducing passage and the pressure reducing chamber are in communication with each other, and the piston chamber and the outside passage are in communication with each other; and the pressure reducing piston is movably provided in the cylinder block so as to be switched between a first preset position and a second preset position, wherein in a situation that the pressure reducing piston is located in the first preset position, the first cylinder block, the second chamber, the pressure reducing passage, and the pressure reducing chamber are in communication with each other; characterised in that in a situation that the pressure reducing piston is located in the second preset position, the pressure reducing piston blocks the communication between the second chamber and the pressure reducing passage and at the same time the gas in the pressure reducing chamber is discharged to the outside through the pressure reducing passage, the piston chamber, and the outside passage. a three-pressure braking mechanism, wherein the three-pressure braking mechanism comprises a first cylinder block, and the first cylinder block has a first working chamber and a second working chamber isolated from each other; and a pressure reducing mechanism, wherein the pressure reducing mechanism comprises a cylinder block, a pressure reducing piston, a partition member, and a pressure reducing chamber, wherein a side wall of the cylinder block is provided with a working passage; the pressure reducing piston has a first end face and a second end face opposite to each other, and a side wall of the pressure reducing piston is provided with a first groove, and an area of the first end face is greater than that of the second end face; the first groove and an inner wall of the cylinder block define a piston chamber; the first end face and the inner wall of the cylinder block define a first chamber, and the second end face and the inner wall of the cylinder block define a second chamber; the cylinder block is configured to be in communication with the first cylinder block, the first chamber is configured to be in communication with the first working chamber, and the second chamber is configured to be in communication with the second working chamber; the partition member is provided in the working passage, and the partition member is configured to partition the working passage into an outside passage and a pressure reducing passage, wherein the outside passage is configured to discharge the gas to the outside; the pressure reducing passage and the pressure reducing chamber are in communication with each other, and the piston chamber and the outside passage are in communication with each other; and the pressure reducing piston is movably provided in the cylinder block so as to be switched between a first preset position and a second preset position, wherein in a situation that the pressure reducing piston is located in the first preset position, the first cylinder block, the second chamber, the pressure reducing passage, and the pressure reducing chamber are in communication with each other; characterised in that in a situation that the pressure reducing piston is located in the second preset position, the pressure reducing piston blocks the communication between the second chamber and the pressure reducing passage and at the same time the gas in the pressure reducing chamber is discharged to the outside through the pressure reducing passage, the piston chamber, and the outside passage.