Dragon's blood is a traditional medicine and used in many countries with different cultures because of its various therapeutic properties. The main bioactive constituents of dragon's blood are flavonoids, which exhibit various pharmaceutical activities, such as haemostatic, analgesic, anticoagulant, and antimicrobial activities and so on, and have attracted the attention of researchers on the development of new drugs. However, the formation process of dragon's blood in nature is very slow, which cannot meet the demand of pharmaceutical uses. Dracaena cambodiana (D. cambodiana) is one of the resource plants of dragon's blood. During the course of tissue culture of D. cambodiana, 6-benzylaminopurine was added in the medium, then red secretion was discovered in the cultured medium. Twelve compounds(1-12), including 11 flavonoids, were determined via the analysis of constituents of the cultured medium by high performance liquid chromatography-electrospray ionization-mass spectrometry(HPLC-ESI-MS) and the results were compared with that of the standards isolated from dragon's blood. Among compounds 1-12, 4,4'-dihydroxy-2-methoxydihydrochalcone(5), 4,4'-dihydroxy-2,6-dimethoxydihydrochalcone(6) and (2S)-7,3'-dihydroxy-4'-methoxyflavane(9) were major compounds of the red secretion, with contents of 15.70, 7.10 and 57.23 mg/L, respectively. Therefore, it is promising that flavonoids from dragon's blood can be obtained from the tissue culture of its resource plants for the purpose of drug development.