Dendrobium was collected from Dendrobium planting regions of Xintian Traditional Chinese Medicine Industry Development co., LTD of Guizhou Province in 2014. The dried stems of the herb (10 kg) were extracted by 95% ethanol solution. DNLA was isolated from the extracts, and analyzed by LC-MS/MS. Alkaloids accounted for 79.8% of DNLA, and mainly contained Dendrobine (C16H25O2N, 92.6%), Dendrobine-N-oxide (C16H25O3N, 3.3%), Nobilonine (C17H27O3N, 2.0%), Dendroxine (C17H25O3N, 0.9%), 6-Hydroxy-nobilonine (C17H27O4N, 0.32%), and 13-Hydroxy-14-oxodendrobine (C16H23O4N, 0.07%). The chemical structures of these ingredients were shown in the Fig. 1A, and the chromatograms of the sample solutions were shown in the Fig. 1B.