Because of the complicated chemical composition of Traditional Chinese Medicines, their chemical profile study has been a great challenge. In the present work, a homologues prediction strategy for rapid screening and identification of C21 steroids in Xiao-ai-ping injection was developed by using an ultra high performance liquid chromatography coupled with high resolution hybrid quadrupole-orbitrap mass spectrometry. This strategy was characterized by the design of C21 steroidal skeleton, substituent group and glycan chain in an orderly way, which could quickly and efficiently screen the interested precursor ions. As a result, a total of 95C21 steroids including 47 potential new ones were identified or tentatively identified, which greatly expanded our knowledge of C21 steroids in Xiao-ai-ping injection. The results indicated that the homologues prediction strategy not only provided an efficient technique to screen and identify target constituents, but also offered a new perspective for discovery new components in Traditional Chinese Medicines.