Despite the huge variety in underlying materials, there is a certain list of common features that are robust across various high temperature superconductors. One of the most salient features in such list is the proximity between superconductivity and antiferromagnetism. The t-J model is often taken as the most natural theoretical model in this context since it reduces to the antiferromagnetic Heisenberg model at half filling. An obviously important theoretical question that has attracted much attention is whether the t-J model contains superconductivity in the doped regime. In this talk, it is shown that the t-J model is intimately connected to the Bardeen-Cooper-Schrieffer (BCS) model with strong on-site repulsive interaction, providing strong support for the existence of superconductivity in the t-J model. We discuss physical implications of such intimate connection in view of the condition under which high temperature superconductivity emerges.