Abstract: Fossil woods were discovered recently in sedimentary intercalation in Miocene Hannuoba basalt in northern Shanxi Province. Primary analysis indicates that the sedimentary environment of these fossil woods belonged to braided channels developed on proluvial fan, and the estimation of tree heights shows that they belongs to averagely tall arbor.Combined with palynological assemblage, paleobotany and mammal fossils, the authors inferred a landscape of moist forest with trend of transition to arid sparse forest steppe, in which sand-gravel mixtures were rapidly carried to lowland by floods caused by seasonal precipitation, and hence these arbors were buried and petrified rapidly.