Abstract: With the continuous exploration of the pathophysiological mechanisms of critical illness, the host response, a "bridge" between different etiologies and the development of critical illness, has received much attention. Host response is the focus of critical illness pathophysiology, and hemodynamics is the core of critical illness development. On the one hand, the host response has a significant impact on hemodynamics; on the other hand, the intervention of the host response through analgesic-sedative-anti-sympathetic therapy and the management of inflammation, immunity, coagulation, metabolism, and bioenergy can stabilize the hemodynamics and achieve the goal of critical illness treatment. A deepening understanding of host response not only enriches the connotation of hemodynamics but also facilitates further study and exploration of the pathophysiological mechanisms of critical illness. Therefore, we describe host response from three aspects: a new understanding of critical illness based on host response, the effect of host response on hemodynamics, and hemodynamic therapy based on the host response.