The invention provides a 3D printing additive manufacturing method of a kettle-shaped thin-wall part. The 3D printing additive manufacturing method of the kettle-shaped thin-wall part comprises the following steps of modeling, specifically, through three-dimensional modeling software, a solid three-dimensional model is established to enable an opening of the kettle-shaped thin-wall part to face upwards; cutting, specifically, through three-dimensional design software, cutting treatment is performed on the solid three-dimensional model to obtain cutting characteristic data; slicing, specifically, through the three-dimensional design software, the cutting characteristic data are spliced in the Z-axis direction to obtain section contour data; filling, specifically, through filling software and the section contour data, path filling is performed on a printing area to obtain laser processing parameters and generate processing information; and scanning and processing, specifically, the kettle-shaped thin-wall part is obtained by printing through the processing information. The 3D printing additive manufacturing method of the kettle-shaped thin-wall part can be used for 3D printing of a thin-wall kettle body with a complex structure, the 3D printing efficiency is improved, the number of supporting structures in the 3D printing is reduced, the generated material waste is reduced, and the later processing work is reduced.