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Biogenic volatile organic compounds (BVOCs) have significant effects on atmospheric chemistry,ozone formation and secondary organic aerosol formation.Considering few investigations about BOVCs emissions in north China where is facing serious air pollution in recent years,emissions of various BVOCs from 24 dominant forest species in Beijing were measured from June to September in 2018,using a dynamic headspace sampling method.More than one hundred BVOCs in the collected samples were identified by using an automatic thermal desorption-gas chromatography/mass spectrometry,and their emission rates based on leaf biomass were calculated.Isoprene and monoterpenes were verified to be the dominant BVOCs emitted from the tree species,accounting for more than 50％ of the total BVOCs.Generally,broad-leaved species displayed high isoprene emission rates,especially the Platanus occidentalis (21.36 μg/(g·hr)),Robinia pseudoacacia (11.55 μg/(g·hr)),and Lonicera maackii (9.17 μg/(g·hr)),while coniferous species emitted high rates of monoterpenes,such as Platycladus orientalis (27.18 μg/(g·hr)),Pinus griffithii (23.11 μg/(g·hr)),and Pinus armandii (7.42 μg/(g·hr)).High emission rates of monoterpenes from the broad-leaved species of Buxus megistophylla (13.07 μg/(g·hr)) and Ligustrum uicaryi (5.74 μg/(g·hr)),and high isoprene emission rate from the coniferous tree of Taxus cuspidata (5.86 μg/(g·hr)) were also observed.The emission rates of sesquiterpenes from each tree were usually 10-100 times smaller than those of isoprene and monoterpenes.Additionally,relatively high emission rates of oxygenated volatile organic compounds and other alkenes than isoprene and monoterpenes were also found for several tree species.