Abstract: The changes of the types of the submucous neurons in the small intestine of the piglets aged 0 days, 5 days and 28 days were studied qualitatively and quantitatively by histochemical and immunohistochemical methods. The results were as follows: The submucous plexus includes external submucosal plexus (ESP) and internal submucosal plexus (ISP). The properties of the nerve fibers in ESP and ISP are different. Most of the nerve fibers in ESP are myelinated nerve fibers, while most of the nerve fibers in ISP are nonmyelinated nerve fibers. As the piglets grow, the submucous plexuses develop fast. And the difference between ESP and ISP becomes more obvious. The study showed that the piglets altered the shapes and the ratio of the different types of submucosal neurons to make the function of the submucous plexuses more perfect.