The quest for next generation spintronic devices has promoted the exploration of ferromagnetism in a two-dimensional (2D) limit which enriches the family of 2D materials. Here, we realized the molecular beam epitaxial growth of atomically flat chromium telluride (CrTe_x) films on Si(111) substrates in the 2D limit and discovered a thickness-dependent structural phase transition with self-intercalation during the growth. Combining the in situ reflection high-energy electron diffraction, scanning tunneling microscopy, x-ray photoemission spectroscopy, and ex situ x-ray diffraction, we found that the first layer of CrTe_x films formed in a CrTe₂ crystalline phase as a buffer layer for further growth. Afterward, the chromium atoms began to intercalate into the layers of CrTe₂, and the Cr₃Te₄ phase dominated the following growth over the second layer. Subsequent superconducting quantum interference device measurements verified the ferromagnetism in the chromium telluride film down to one layer limit. Our results provide important information on the structural phase transition during the growth of CrTe_x films, which would be an ideal platform for studying ferromagnetism in 2D systems, and the growth of high-quality CrTe_x films on Si substrates would benefit the further applications of 2D ferromagnetic films.