Abstract: Aiming at the technical problems of machining allowance detection and coordination of large 3D printing titanium alloy parts, the new 3D scanning technology was used to scan and compare the blank accurately, and the remaining quantity distribution results were obtained. According to the margin distribution results, the rough machining allowance coordination of the blank was realized, which effectively solved the problem of margin coordination with large blank margin difference and small local margin. It provides important technical support for the margin detection and analysis of irregular and large structural parts.