The qualifications of compressor cylinder were tested by three dimensional marking measuring instrument. The steps and methods of testing small laps between 10 cylinder nozzles,including R65, R92, R55, and 181 laps, nozzles and midfaceted flanges were discussed. Among them, the pattern detection method was used for the middle flange, which provided basis for cleaning process and repairing castings. The structure of the equipment is complex, and it is the highest temperature bearing part of the whole gas turbine. Its performance requirements are high, and it is difficult to test its parameters. The technical scheme has certain reference value for similar equipment detection.