The parallel differential confocal three-dimensional imaging method realizes multi-point parallel detection by dividing the illumination light into multiple isolated beams, which solves the problem of low imaging efficiency caused by point-by-point scanning of traditional differential confocal imaging. It is an ideal fast and high-precision three-dimensional imaging method. However, both non-homogeneous illumination and field curvature of an optical imaging system induce errors in the measurement results during the process of parallel differential confocal detection. The effects of inevitable non-homogeneous illumination and field curvature of an optical system during the wide-field imaging process on the parallel differential confocal axial measurement are analyzed, a wide-field error correction method is proposed, and a theoretical model of wide-field error correction is established for the parallel differential confocal axial measurement. The experimental results show that the proposed method can effectively suppress the influence of non-homogeneous illumination on the measurement results and correct the axial measurement error caused by the field curvature of the optical imaging system. It ensures the universality of parallel differential confocal nanometer-scale axial measurement accuracy in the full field of view. The implementation process of this method is simple and convenient, and it is also applicable to error correction of other parallel confocal detection methods.