Objective To investigate changes in the collagen expression and elastic modulus in scleral tissues of experimental high myopia, so as to further explain the mechanism of high myopia. Methods Twenty one-month-old New Zealand white rabbits were monocularly treated by eyelid suturation randomly to build an experimental high myopia eye model. Eyes without such operation were set as the normal control. After 60 days, the experimental high myopia eye models were successfully established by measuring the eye axis. The eyeballs were obtained to assess three regions of the sclera (anterior, equatorial, and posterior area). The three regions of the scleral tissues were separately divided into four groups. The first group was made into scleral strips for elastic modulus measurement using an Instron5544. The second group was hematoxylin-and-eosin stained for observation of the scleral structures. The third group was used for electron microscopy to observe the size distribution of collagen fibrils. The last group was homogenized, and the concentration of hydroxyproline was measured to determine the collagen content. Results The elastic modulus, collagen content, and diameters of the collagen fibrils of each scleral region increased with age. The posterior sclera of high myopia had looser collagen fibril arrangement, less hydroxyproline concentration, and lower elastic modulus than the normal eyes. However, there was no significant difference as for the anterior and equatorial sclera. Conclusions The remodeled posterior sclera of high myopia has a looser collagen fibril arrangement, less collagen, and lower elastic modulus, which easily causes expansion and deformation and thus lead to high myopia. The research findings provide the theoretical guidance for high myopia prevention by targeting the collagen during early development.