Interferon tau (IFNT), a type I IFN produced by the conceptus trophectoderm, is the signal for maternal pregnancy recognition in ruminants. The purpose of this study was to investigate whether IFNT effected on the proliferation of ovine trophectoderm cells in an autocrine manner. Elongated ovine conceptuses (Days 15, Day 0 = day of mating) were collected for isolation of mononuclear ovine trophectoderm (oTr-1) cells, and conceptuses (Days 15 and 20, n = 4 and 3, respectively) were collected for RNA extraction. We demonstrated that the IFNT receptor, IFNAR1, was expressed in trophectoderm of day 15 and 20 conceptuses. Interestingly, the ovine trophectoderm cell line oTr-1 cultured in the presence of recombinant bovine IFNT (rbIFNT) displayed increased expressions of IFN-stimulated genes (ISGs), such as IFN-stimulated gene 15 (ISG15), 2-5-oligoadenylate synthetase 1 (OAS1) and bone marrow stromal cell antigen 2 (BST2). Meanwhile, the presence of rbIFNT in the culture media could promote the cell proliferation in a dose-dependent manner. Furthermore, the connective tissue growth factor, which has diverse functions in cell proliferation and is involved in conceptus elongation, was upregulated in oTr-1 cell by rbIFNT treatment in vitro. These data indicated that IFNT could act as an autocrine factor to regulate trophectoderm cell proliferation.