Fundus retinopathy is the cause of most ophthalmic diseases. Optical coherence tomography (OCT) has been widely used in the diagnosis of ophthalmic diseases because of its non-invasive and rapid imaging features. In this paper, a dither removing method is proposed for three-dimensional OCT retinal image based on curve fitting. The OCT retina image boundary is extracted by preprocessing, and the offset of each frame slice image is calculated by least squares curve fitting. The results show that the proposed method has a significant correction effect on the distortion of the OCT retina three-dimensional reconstructed images.