Dendrobium pendulum Roxb. is a perennial epiphytic herb of Orchidaceae with high health and medicinal value,being rich in alkaloids.Component analysis and relative quantitative analysis of alkaloids were carried out by ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF-MS) from the stems,flowers and leaves of D. pendulum.Fifteen alkaloids were found and identified by methanol and chloroform extraction, in which seven compounds were octahydroindolizine alkaloids: dendrocrepine (1),dendrocrepine C (2),credidamine (3),crepidine (5),dendrocrepidine B (8),dendrocrepidine D (9),homocrepidine B (10);Seven compounds were sesquiterpene alkaloids: dendrobine (4),dendramine (6),nobiline (7),mubironine A (11),N-isopentenyl-dendroxine (12),N-isopentenyl-dendrobine (13),findlayines D (14);One amide alkaloid compound was N-p-cinnamoyl-tyramine (15).Alkaloids were firstly discovered from D. pendulum. The main alkaloids were octahydroindolizine alkaloids in D. pendulum,and the contents of crepidine and dendrocrepidine B were high.Alkaloids contents from high to low were flowers,leaves and stems in different parts of the plant.The alkaloids of flowers were mostly octahydroindolizine type,and the alkaloids of stems were mainly sesquiterpene type.