Abstract: Chromatic confocal 3D profiler has high precision, large measuring range and strong adaptability. The key component is the objective lens with axial dispersion. The nonlinear dispersion of axial dispersion and wavelength of the dispersion objective lens reduces the overall performance of theprofiler. In this paper, by analyzing the principle of confocal method to detect surface topography and the conditions for producing linear axial dispersion, the design indexes and requirements of confocal optical system are given, and a super-dispersive objective lens has been designed.The objective lens has four magnification structures in series dispersing the focus of wavelength between 400 and 700 nm to 30 mm longitudinal range. Through linear regression fitting of the defocusing amount and linearity of the wavelength, it is obtained that the coefficient of determination is 1, greatly improving the linearity of dispersion.