Abstract: Aiming at the problem that excessive defects such as inclusion and porosity were found on the non-processed surface during the fluorescence penetration test of a certain type of guide blade in the machining stage, leading to a large number of discarded blades in multiple batches, the process flow of the blades in the blank and machining stages was analyzed. The blades of normal sand blowing process were observed with scanning electron microscopy, and the influence of blade corrosion process on the fluorescence detection results was analyzed. Finally, it is determined that incomplete surface cleaning before fluorescence permeation detection in the blank stage is the main reason for the discovery of excessive defects in the machining stage. Therefore, the pre-corrosion process was added before the final inspection process of fluorescence permeation test in the blank stage, which significantly improved the defect detection rate of the blade in the blank stage and reduced the scrap rate of the blade in the machining stage.