Traditional Chinese medicine (TCM), including herbal and folk medicine have been widely applied in healthcare field for a very long time. Based on the principle of kinetics, pharmacokinetics of TCM was developed to investigate the absorption, distribution, metabolism and excretion of active ingredients/components, single or mixed formulations, as well as the relationship between concentration and efficacy presented. Due to the complexity of TCM and its preparation, selection of molecules as markers for detection has become very difficult. So far, in which way or what indicators can be chosen for representing the pharmacodynamic action of single TCM or mixed is still controversial. Currently, a widely accepted approach is that the action of mixed preparation can be correlated by detecting pharmacokinetic behavior of one or several known active ingredients. According to the complexity of TCM, we presented a new concept of pharmacokinetic (PK) marker. The PK Marker should possess three conditions: (1) PK marker must be associated with efficacy, (2) PK marker exists in biological sample and can be determined by analytic method, and (3) PK marker should reflect the relationship between concentration and time. In TCM, four elements, "king-minister-assistant-guide", are the basic prescription principles for the individual therapy in TCM. We presented an idea of Point-line-area-cubic for four elements of TCM to study herb-herb interactions.