The utility model discloses an acidifying and passivating device for a stroke sleeve of a CRDM (Control-Rod Device Mechanism) rod and an inner surface of a seal housing and belongs to surface treatment devices and the technical field. The acidifying and passivating device comprises a liquid tank set, a control center and a passivating tool, wherein the liquid tank set consists of an oil removal liquid tank, a washing liquid tank, a passivating liquid tank and a finish washing liquid tank, each liquid tank is communicated with the control center through independent liquid supply pipe and liquid return pipe, and the control center controls the liquid tank and the passivating tool to form an independent acidifying and passivating circuit. The acidifying and passivating device disclosed by the utility model is skillful in concept and reasonable in design, can satisfy acidification and passivation of the stroke sleeve of the rod and the inner surface of the seal housing and has the advantages of small investment, high operating efficiency and good passivating effect on the inner surface. For the inner surface passivated of a part, no visible oxidized spots are found under a 5-time magnifying lens, and liquids in the liquid tanks can be recycled for times.