All-metal sealing soluble bridge plug

The invention belongs to the field of oilfield downhole tools, and particularly relates to an all-metal sealing soluble bridge plug which comprises a central pipe, an upper outer pipe and a lower outer pipe are sequentially sleeved on the central pipe, an annular space is reserved between the upper outer pipe and the central pipe, and an upper piston A and a lower piston B are arranged in the annular space and are respectively a piston A and a piston B; wherein the piston A is fixedly connected with the center pipe in a sealed mode and is connected with the upper outer pipe in a sliding and sealed mode, the inner side of the upper outer pipe of the piston B section is provided with a diameter expanding step which plays a role in limiting the piston B, the piston B is connected with the upper outer pipe in a sliding and sealed mode, and the piston B is connected with the center pipe in a sliding and sealed mode, so that the piston A, the piston B, the center pipe and the upper outer pipe define a gas cavity. A