Objective To find out the bioactive constituents in the stem of Lonicera japonica and to carry out a systematic study on the chemical constituents of the plant. Methods Three compounds were isolated from the plant by means of solvent extraction and column chromatography, and their structures were elucidated by spectral analyses. Results All these compounds were identified as luteolin (Ⅰ), loga-nin (Ⅱ), r-1-(4-hydroxy-3-methoxy-phenyl)-trans-2, cis-3-dihydroxymethyl-7, 8-dihydroxy-6-methoxy-1, 2, 3, 4-tetrahydro-naphthalene (Ⅲ), respectively. Conclusion Compound Ⅲ is a new compound named as japenol.