OBJECTIVE： To study pharmacognosy of Melilotus officinalis. METHODS： Qualitative identification of M. officinalis was conducted in respects of morphology， macroscopic characters， microscopic identification， UV spectra for medicinal extracts and IR spectra for medicinal powder. RESULTS： Nineteen bundles of rays were distributed in the radial bundle of root cross section of M. officinalis. The main vein vascular bundle of leaf cross section had a palisade tissue passing over it. The pith of the cross section of the stem occupied 4/5 of the whole cross section. The cross section of the leafstalk was heart-shaped， and unequal vascular bundles arranged in a triangular array. There were glandular hairs， which consist of three cells， and unicellular non glandular hairs in leaf epidermis. The crystal fibers of calcium oxalate crystals and infinitive blowhole were found in the leaves； glandular hairs and non glandular hairs could be found in the leafstalk under tissue dissociation； verrucous like protuberance and threaded catheter were found on the surface. The UV spectrum of extract and two order derivative IR spectrum of the medicinal powder showed obvious characteristics. CONCLUSIONS： Established method can be used for pharmacognostic identification of M. officinalis.