A UPLC-Q-TOF-MS method was developed for the analysis and identification of main chemical constituents in the extract of Cordyceps liangshanensis, by an Agilent SB-C18（50mm×4.6mm，1.8μm） column with gradient elution using of 0.1% formic acid in water and acetonitrile as mobile phase at a flow rate of 0.25mL/min.The column temperature was set at 30℃.MS analysis was based on information associated mode（IDA） with positive and negative ions collection. By using feature of PeakView such as Formula Finder，matching the mass spectrometry data of each chromatographic peak in the database and the cleavage law of each peak′s level two fragment，total of 27 compounds in Cordyceps liangshanensis were identified，in which 8 compounds in Cordyceps substance had never been reported before. The main chemical constituents include alkaloids，glycosides，nucleosides，amino acids，etc. The method is accurate，reliable and efficient，and is suitable for the rapid identification of ingredients in Cordyceps liangshanensis. It provides a reference for the development and utilization of Cordyceps liangshanensis and clarification of its efficacy and material basis.