The utility model discloses a micro pressure relief flange for a power transformer moisture absorber, which comprises a flange body and a conical valve. A valve hole is arranged on one side of the flange body, a first discharge hole is arranged between the valve hole and a central hole of the flange body, a second discharge hole is arranged between the valve hole and the bottom face of the flange body, and the front end of the conical valve is matched with the valve hole. By adopting the technical scheme, the micro pressure relief flange installed between the moisture absorber and a connecting pipe is used as a bypass pressure relief passage, can avoid the operation of changing a tripping position of heavy gas protection into a signal position during running due to the fact that oil flow speed exceeds a set action value and causes malfunction of main transformer heavy gas during detachment of the moisture absorber, reduces work load of field operation, and guarantees operation reliability of a transformer during operation.