The invention provides an auxiliary support structure suitable for an inclined overhanging thin-walled structure. The auxiliary support structure is used for supporting the inclined overhanging thin-walled structure on a base plate during the melting material increase manufacturing process of a laser selective area and is particularly suitable for the inclined overhanging thin-walled structure which is provided with a dip angle greater than 45 degrees, is spaced from the base plate with certain distance, and has a thickness smaller than 3.5 mm; a grid support is adopted between an overhanging end and the forming base plate; a sheet type solid support is adopted on the back of the overhanging thin-walled structure; the grid support and the solid support are fixedly connected to form an entirety, so that an overhanging part is prevented from buckling deformation, interlayer dislocation and other defects, and the grid support part is prevented from a pull crack and breakage due to rub to further cause collapse of the overhanging part and other problems; and compared with the entire solid support, the grid support is greatly reduced or decreased in the aspects of removing difficulty, workload, production cycle and cost.