Abstract: The feasibility of measurement of straightness motion error for CMM based on Sequential Two Points Method was researched, the principle of measurement of Sequential Two Points Method was introduced and errors from the misalignment and adjustment sensors were analyzed quantificationally. According to the straightness motion error for existing CMM, the results indicated that the method of Sequential Two Points to measure straightness motion error，which can content with the requirements of the measurement accaracy，is practical and reliable.

Key words: Sequential Two Points Method (STPM), CMM, Straightness motion error, Slide