Precise, efficient, fast and convenient detection is an indispensable method and link in the machinery industry to ensure the quality, reputation and market. Three coordinates are now the most rapid and accurate detection tools, and how to make good use of three-dimensional software to better serving us? For irregular parts space size measurement, the measured elements are transformed into the existing three-coordinate identifiable geometric elements, and three coordinate measuring machine measurement software (PC - DMIS) is used by fitting and constructing measured characteristic elements, and measuring program is compiled to solve the technical problems of different parts of the irregular surface space intersection measurement.