In order to meet the requirements of high-precision and non-contact measurement of small diameter deep hole parts, a set of high-precision optical measurement system suitable for large measurement range was developed. Based on the principle of dispersion confocal measurement, a micro displacement system is established, and a high-resolution optical measurement system is formed by combining the spectral analysis technology. Firstly, based on the dispersion confocal principle, the structure of dispersion objective lens is designed by using Zemax software. Secondly, the creeping structure is designed, and the motor is used to drive the reflector rotating to complete the radial geometric dimension measurements of different sections of the deep holes. Thirdly, the system error is analyzed by least square method and is compensated. Finally, an experimental platform was built to verify that the measurement range reached 5 mm and the measurement accuracy was better than 3.3 μm. It has the advantages of high measurement accuracy, large measurement range and compact structure, which is of great significance to solve the problem of the measurement of the inner diameter of small size deep hole parts.