Abstract: The positioning size measurement of the space diagonal holes on many large -scale product parts is difficult and complicated, time-consuming, costly, and inefficient. In this paper, starting from the structure and measurement difficulties of the space diagonal hole of a certain part, the research method is carried out, a convenient and efficient measurement scheme for field use is also developed, and the feasibility of this method is verified through an instance. This measurement method can realize the precise measurement of the positioning characteristics of the space diagonal holes at any angle, which has certain reference significance for the detection of alien parts, reverse engineering surveying and mapping.