Metal bridge plug capable of being degraded completely

The invention discloses a metal bridge plug capable of being degraded completely. The metal bridge plug comprises a center pipe, an upper expansion block and a sealed chamber, wherein the upper expansion block and the sealed chamber are sequentially arranged outside the center pipe in a sleeving mode with annulus formed in between, an upper connector is arranged at the top end of the center pipe, and a lower expansion block is arranged at the bottom end of the center pipe; the sealed chamber is a cylinder structure capable of deforming through expansion and shrinkage, and a pressure relief hole is formed in the side wall of the sealed chamber; the top end of the upper expansion block is fixed to the top end of the center pipe through a shear pin, and the upper expansion block can move relative to the center pipe and squeeze the sealed chamber to achieve setting; a first locking mechanism on the outer wall of the center pipe is matched with a second locking mechanism in the upper expansion block to lock the setting position. Through cooperation of the center pipe, the upper expansion block and the sealed chamber, it is guaranteed that setting of the bridge plug does not occur too early during descending; the set bridge plug is degraded gradually and completely after making contact with formation water, follow-up plug drilling is omitted, and production efficiency is improved greatly.