Objective Cardiac Qi-Deficiency(CQD) is one of the main syndrome of TCM (Traditional Chinese Medicine). Based on Qi-Blood Transportation theory and blood-tissue fluid circulation analysis, a hemodynamics model describing CQD was set up to explore its dynamics mechanism.Methods Through analyzing the calculating results, the regulary influence of the vascular hemodynamics parameter′s changes on the interstitial edema's (main symptom of Qi-Deficiency) formation has been obtained, and quantitative relationship between the vascular hemodynamics parameters and the edema degree was given.Results To compare the theoretical results with the CQD research of clinical and animal experiments, it showed that our model could explain the physiological and pathological mechanism of CQD quantitatively. When the vascular parameters (for example, the total blood volume, the remote vascular resistance, and the cardiac contract force ) change, the interstitial volume will increase, which could lead to the decrease of the concentration of the protein and other nutritious contents.Conclusion the Qi content of CQD is closely relative to the nutrition concentration in the tissue fluid, when more water moves from blood to the inter-tissue, the content concentration in tissue-fluid will decrease, which will affect cell's physiological function and lead to symptoms of Qi-Deficient.