An absorbable iron based medical instrument implant and a manufacturing method. The iron based alloy medical instrument implant comprises an iron based alloy (11) a decomposable polymer layer (13) disposed on a surface of the iron based alloy (11) and a tannic acid chemical conversion film (12) disposed on the surface of the iron based alloy (11). After the medical instrument implant is implanted into a body the tannic acid chemical conversion film (12) is configured to protect the iron based alloy (11) coated thereby from being in contact with a body fluid thereby ensuring a mechanical performance requirement of the instrument implant early in a clinical trial. Furthermore the absorbable iron based medical instrument implant has a decreased size and produces a decreased amount of a corrosive byproduct after being implanted facilitating faster absorption or elimination of the corrosive byproduct.
