Disclosed is a welding spot quality detection method. The detection method comprises the following steps that A, s set of jacking device is provided; B, sealant at a mounting edge of an outer duct casing is removed, adjusting bolts is operated by a spanner, so that the adjusting bolt can rotate three to five circles; a casing wall, away from one side of the mounting edge, of a welding spot is pressed by a pressing block; separation condition of the mounting edge is observed, measurement is carried out by a filler gauge, if a 0.1 filler gauge cannot be inserted, or the 0.1 filler gauge can be inserted but cannot pass through the welding point, and the quality of the welding joint meets the requirement; and if the 0.1 filler gauge can be inserted and can pass through the welding joint, the welding joint is disconnected, and the quality of the welding joint is not up to the requirement. According to the welding spot quality detection method, the quality of the welding joint of the outer duct casing can be checked without removing an aircraft engine from an aircraft, the efficiency and accuracy of the external field maintenance work are greatly improved, and the maintenance work cycleis greatly shortened.