Traditional Chinese medicine (TCM) has contributed greatly to human health in past several thousand years. Today, the development of TCM is facing two obstacles: (i) quality control of herbal extract; and (ii) action mechanisms not known. Among thousands of complex TCM formulations, Danggui Buxue Tang (DBT) is the simplest one. DBT is used to treat ailments in women and contains only two herbs, Astragali Radix (Huangqi; AR) and Angelicae Sinensis Radix (Danggui; ASR). The weight ratio of AR to ASR in DBT must be 5:1, as stipulated in AD 1247. By using DBT as a model formula, we develop a strategy to reveal the complexity of a traditional TCM formula. There are 3 levels of research directions: (i) the preparation of DBT and its rationale behind; (ii) the traditional theory of DBT is elucidated by chemical and biological determinations; and (iii) the action mechanisms of DBT are revealed. Through the chemical, biological, genomic and proteomic studies, a possible direction in resolving the preparation mythologies, pharmacological and mechanistic analyses of a TCM decoction is being proposed here. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.