Abstract: The axial spacing measurement between optical elements is of great significance to the positioning and adjustment of precision optical systems. Aiming at the problems of complex dispersive objective lens structure and small dispersion range in the existing dispersion confocal measurement system, a method for measuring the axial spacing of optical elements based on the method of polarization diffraction dispersion confocal was proposed. The axial dimension of a traditional refractive confocal lens with a few hundred millimeters and the complex alignment requirements were simplified to a single-chip lens with a few millimeters, which simplified the system structure. The results of lens spacing and thickness measurement experiments show that the spacing measurement error is 10 μm.