The stress response is a non-specific adaptive physiological reaction that occurs when the organism is exposed to internal or external environmental stimuli, serving to maintain homeostatic balance. Its regulation involves highly complex neural mechanisms. The hippocampus, the bed nucleus of the stria terminalis (BNST), and the paraventricular hypothalamic nucleus (PVN) are key brain regions that play crucial roles in stress regulation. Focusing on the functional connectivity of the hippocampus-BNST-PVN neural circuit, this article systematically elucidates the multilevel effects of stress on synaptic transmission, synaptic plasticity, neural network integration, and related molecular mechanisms from microcosmic neurotransmitters to macroscopic neural circuits. These insights provide an important perspective for advancing our understanding of the neurobiological basis of stress and for developing new intervention strategies.