Objective To investigate the changes of morphological structures and biomechanical properties of scleral tissues in rabbits at different month ages. Methods The eyeballs of 1, 2 and 3 month-old New Zealand white rabbits were obtained for measuring the diameter and axial length, and the thickness of scleral tissues. Part of the scleral tissues was used to observe scleral structures with HE staining, some other part was used to observe collagen fibrils by electron microscope, and the left part were cut into strips and used to test the elastic modulus of the sclera on Instron 5544 system. Results The diameter, axial length of eyeballs and the thickness of the sclera were increased with month age. The elastic modulus of scleral tissues was also increased with month age. The numbers of scleral fibroblasts were decreased and the numbers of fiber bundles were increased with month age. The diameters of collagen fibrils were increased with month age. Conclusions In the post-embryonic stages, the structures of eyeball and sclera are changed continually, with growing numbers of thicker collagen fibers, and the biomechanical properties of scleral tissues are improved correspondingly. The mechanism of post-embryonic development in sclera is further explained in the study, which can provide theoretical guidance for prevention of sclera-related diseases.