In traditional Chinese medicine, internal organs imply five viscera and six bowels. Five viscera mean liver, heart, spleen, lung and kidney, and six bowels mean gallbladder, small intestine, stomach, large intestine, urinary bladder and triple energizer. Also, meridian system represents the passage of metabolites in the human body. In this paper, we deal with construction of Petri net model of internal organs and meridian based on traditional Chinese medicine. At first, we introduce relations of mutual generation and mutual restriction between five viscera to make a basic Petri net model of five viscera based on five-elements theory. Analyzing the relation between five viscera and six bowels, we propose a model of internal organs that include five viscera and six bowels. After that, through investigating the syndrome of internal organs as well as the function of pericardium meridian, we propose a Petri net model including internal organs and meridians by combining the model of i...