A steam sterilizer of a hemodialyzer belongs to the field of medical instruments. The steam sterilizer is particularly applied to the sterilization of special articles which can resist temperature of below 125 DEG C and have low pressure withstanding performance. The steam sterilizer comprises a sterilizing room (1), an indoor air inlet valve (2), a saturated steam valve (3), an indoor slow discharge valve (4) and a vacuum-piping system (5) loop, wherein the sterilizing room (1) is connected with the indoor air inlet valve (2) loop, the saturated steam valve (3) loop, the indoor slow discharge valve (4) loop and the vacuum-piping system (5) loop respectively. The steam sterilizer has the advantages of good sterilizing effect, safety, reliability, high working performance, convenience in operation and maintenance, and the like.