Abstract: OBJECTIVE To investigate the reciprocal transformation of rhubarb five anthraquinones constituents in extracting and refining process. METHODS The method of HPLC was used to determine the content of five anthraquinones constituents in the ten batches of herbs and extracts respectively. And relative content of aloe-emodin, rhein, emodin, chrysophanol and physcion in rhubarb medicine material was compared with that in extracts of Rhubarb. Five anthraquinones reference substances were used to review the conversion between five anthraquinones constituentsin in the simulated extracting and refined process of rhubarb. RESULTS The ratio of five anthraquinones constituents in extracts had obviously changed compared with that in Rhubarb medicine material. The proportion of rhein increased in extract. But the transformation was not been found among the five reference substances. However, only rhein reference substance could partly be transformed into emodin in extracting and refined process with the addition of Scutellariae Radix extract close to Rhubarb in genetic relationship. CONCLUSION The results provide reference for the extracted and refined process of rhubarb anthraquinone study.