The invention relates to the technical field of electric package, in particular to a welding tool and method for an airtight type high silicon aluminum package shell body. The welding tool comprises abase and a pressing plate, the base is internally provided with a limiting groove matched with the shape of the package shell body, the pressing plate is provided with a plurality of flow guiding grooves penetrating through the pressing plate, when the pressing plate is connected with the base, the flow guiding grooves communicate with the to-be-welded area of the package shell body, thus the flow guiding grooves of the pressing plate are connected with the to-be-welded area of the package shell body, thus the package shell body is limited by the welded tool, the position is fixed, the heat is conducted out from the base and the cover plate during welding, meanwhile, welding point protection gas can be effectively conducted in the welding process through arrangement of the flow guiding grooves, it is ensured that no impurity enters a molten pool in the welding process, thus the welding quality of the package shell body is great, the influence of welding heat on electron devices in thepackage shell body is decreased, and great airtight performance is achieved.