1. A method for acquiring a retina structure from an optical coherence tomographic image, comprising: calculating a region of interest (ROI) image of a single retina optical coherence tomographic source image; performing a Gaussian filtering on the ROI image; calculating a first estimated boundary position of a first layer boundary and a second estimated boundary position of a second layer boundary after the Gaussian filtering, using a multi-resolution method; simplifying an active contour model, and refining the first layer boundary and the second layer boundary respectively using the simplified active contour model according to the first estimated boundary position and the second estimated boundary position, to obtain a first initial boundary position of the first layer boundary and a second initial boundary position of the second layer boundary; smoothing the first initial boundary position and the second initial boundary position using a Savitzky-Golay filtering method, and taking the smoothed first initial boundary position and the smoothed second initial boundary position as a segmentation position of the first layer boundary and a segmentation position of the second layer boundary, respectively; acquiring segmentation positions of rest layer boundaries in the ROI image according to the segmented position of the first layer boundary and the segmented position of the second layer boundary, to obtain segmentation positions of all the layer boundaries in the ROI image.