White matter degenerates with normal aging and accordingly results in declines in multiple brain functions. Previous neuroimaging studies have implied that the white matter is plastic by experiences and contributory to the experience-dependent recovery of brain functions. However, it is not clear how and how far enriched environment (EE) plays a role in the white matter remodeling. Male rats exhibit earlier and severer age-related damages in the white matter and its myelinated fibers than female rats; therefore, in this current study, 24 middle-aged (14-month-old) and 24 old-aged (24-month-old) male SD rats were randomly assigned to an EE or standard environment (SE) for 4 months prior to Morris water maze tests. Five rats from each group were then randomly sampled for stereological assessment of the white matter. Results revealed that EE could somewhat induce improvement of spatial learning and significantly increase the white matter volume, the myelinated fiber volume and the myelinated fiber length during normal aging. The EE-induced improvement of spatial learning ability was significantly correlated with the EE-induced increase of the white matter and its myelinated fibers. We suggested that exposure to an EE could delay the progress of age-related changes in the white matter and the effect could extend to old age.