This study analyze two multiplicative errors of parallel object-side differential axial measurements method under the surface reflectance change and illumination non-uniformity condition, and an error correction model is proposed. The mathematical expression of the image gray matrix which can characterize multiplicative disturbance interference is constructed, and the multiplicative disturbance interference errors can be eliminated via logarithmic difference, which corrects the errors. The verification of the error correction model is then achieved by analyzing two comparative experiments. In the experiments, the morphometry of the step sample with 4.739 μm height and 50 μm period is measured. The relative error of the measurement is reduced from 2.91% before correction to 0.78% after correction. Under low-magnification objective lens and illumination inhomogeneity measurement condition, a fast three-dimensional morphology experiment is conducted on coins with uneven surface reflectance. The relative deviation of the measurement result is 1.62% compared with those obtained by optical surface profiler. Both the experimental analyses demonstrate that the proposed method can successfully correct the effects of multiplicative errors and improve the adaptability. The proposed method can provide microtopography detection for on-line detection of intelligent manufacturing with high applicability, efficiency, and precision.