Abstract: Systems, Minstry of Education, College of Earth and Environmental Science，Lanzhou University，Lanzhou 730000)Many studies show that n­alkane distribution from different modern vegetation are very different，and it is still a hot debate about using the n­alkane distribution to reconstruct the paleovegetation in loess deposition，especially the n­alkane distribution of conifer. We collected familiar some vegetation and surface soil in the Western Loess Plateau，including 3 kinds of conifer，and analysed by GC for the distribution model of n­alkanes. The results revealed that 10 kinds of wood vegetation showed heavy­molecular­weight(HMW)homologues of the n­alkanes distribution with the main peak of C27 or C29，while in 3 kinds of herb n­alkanes，the HMW homologues distributions of C31 or C33 are the main peaks，which show a completely different distribution feature from woody plants. The 3 kinds of conifer are typical of wood plants with the main peak of C29 without C31 main peak. The n­alkanes distribution in the modern surface soil was directly related to the quantity of the input of the vegetation. For different sites，wood vegetation and the herb vegetation had different input，so there are different n­alkanes distributions in the associated surface soils. The distributions of n­alkane from decomposed leaf and fresh leaf have same main peaks，indicating the leaf decay does not have significant impact on the main peaks. In this research area the same wood plant in different site showed the same main peaks of n­alkane，but the herb plant showed different. The growth environment will affect the main peaks of n­alkane of herb plant，but not for the wood plants. Depend on the research of modern vegetation and surface soil，therefore，the main peaks of n­alkane in loess sediments could be comparatively reliable in palaovegetation recunstructions.