In this work, using the model of random phasor sums, the intensity probability density distribution of the signal of an optical coherence tomography (OCT) structure is described, the probability density distribution of the amplitude difference signal is derived, and the threshold model of the dynamic and static regions of the difference image is theoretically determined. A set of swept source optical coherence tomography systems that can scan and image the microvascular of the human skin is used to generate binarized images through a threshold model, combining the existing cross-correlation images based on volume data and binarized images in the laboratory. Results show that the proposed model can reduce the speckle noise and obtain clear structural information.